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Feb 96 Challenge
Volume Number:12
Issue Number:2
Column Tag:Programmer’s Challenge

Programmer’s Challenge

By Bob Boonstra, Westford, Massachusetts

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

Intersecting Rectangles

The Challenge this month is to write a routine that will accept a list of rectangles and calculate a result based on the intersections of those rectangles. Specifically, your code will return a list of non-overlapping rectangles that contain all points enclosed by an odd (or even) number of the input rectangles. The prototype for the code you should write is:

void RectangleIntersections(
 const Rect inputRects[], /* list if input rectangles */
 const long numRectsIn,   /* number of inputRects */
 Rect outputRects[], /* preallocated storage for output */
 long *numRectsOut,/* number of outputRects returned */
 const Boolean oddParity  /* see text for explanation */
);

The parameter oddParity indicates whether you are to return rectangles containing points enclosed by an odd number of the numRectsIn inputRects rectangles (oddParity==true) or by an even (nonzero) number of rectangles (oddParity==false). Sufficient storage for the output will be preallocated for you and pointed to by outputRects.

As an example, if you were given these inputRects:

 {0,10,20,30}, {5,15,20,30}

and oddParity were true, you might return the following list of outputRects:

 {0,10,5,15}, {0,15,5,30}, {5,10,15,20}

It would also be correct to return a result that combined the first of these rectangles with either of the other two. If oddParity were false, you would return the following list for the example input:

 {5,15,20,30}

The outputRects must be non-empty and non-overlapping. In the example, it would be incorrect to return the following for the odd parity case:

 {0,10,5,30} {0,10,20,15}

The outputRects you generate must also be maximal, in the sense that each edge of each of the outputRects should pass through a vertex of one of the inputRects. That is, for example, I don’t want you to return a 1¥1 rectangle representing each point enclosed in the desired number of inputRects. Before returning, set *numRectsOut to indicate the number of outputRects you generated.

If you need auxiliary storage, you may allocate any reasonable amount within your code using toolbox routines or malloc, but you must deallocate that storage before returning. (No memory leaks! - I’ll be calling your code many times.)

This native PowerPC Challenge will be scored using the latest Metrowerks compiler, with the winner determined by execution time. If you have any questions, or would like some test data for your code, please send me e-mail at one of the Programmer’s Challenge addresses, or directly to bob_boonstra@mactech.com. Test data will also be sent to the Programmer’s Challenge mailing list, which you can join by sending a message to autoshare@mactech.com with the SUBJECT line “sub challenge YourName”, substituting your real name for YourName.

Two Months Ago Winner

Eight of the 13 solutions submitted for the Find Again And Again Challenge worked correctly. Congratulations to Gustav Larsson (Mountain View, CA) for submitting an entry that was significantly faster than the others. The problem was to write a text search engine optimized to operate repeatedly on the same block of text. A variety of optimization techniques were represented in the solutions, a couple of which are highlighted in the table of results below. Several people optimized for the case where the same word was repeatedly searched for. Some of my tests included this case, and those results are in the columns headed “repeat.” The “random” columns shows results for tests that searched for random occurrences of random words. Each of the tests were run under conditions where only 64KB of auxiliary storage was available, and where much more memory was available. These conditions were weighted 20% and 80% respectively in calculating the total time, since the problem statement promised that ample memory would usually be provided. You can see that Gustav’s solution performed reasonably well when memory was scarce, and very well when memory was plentiful.

Gustav’s solution hashes as many words of the input text as possible in the initialization routine. He uses the Boyer-Moore-Horspool algorithm to find words in any text that was not parsed during initialization. Other features of the approach are described in the well-commented code.

Here are the times and code sizes for entries that passed by tests. Numbers in parentheses after a person’s name indicate that person’s cumulative point total for all previous Challenges, not including this one.

64K Memory >>64K Memory code

Name repeat random repeat random time size

Gustav Larsson (67) 1814 3773 62 111 1255 3584

Tom Saxton 46 16400 197 459 3814 2000

Xan Gregg (81) 27 2907 1316 2835 3907 1664

Kevin Cutts (46) 1760 3234 1760 2809 4654 1600

Joseph Ku 8856 14570 121 509 5189 1584

David Cary 60 22665 499 1000 5745 2124

Eric Lengyel (40) 34 10221 29 4697 5831 1188

Ernst Munter (110) 2036 2053 2287 4603 6330 2976

Top Contestants of All time

Here are the Top Contestants for the Programmer’s Challenges to date, including everyone who has accumulated more than 20 points. The numbers below include points awarded for this month’s entrants.

Rank Name Points Rank Name Points

1. [Name deleted] 176 11. Mallett, Jeff 44

2. Munter, Ernst 110 12. Kasparian, Raffi 42

3. Gregg, Xan 88 13. Vineyard, Jeremy 42

4. Larsson, Gustav 87 14. Lengyel, Eric 40

5. Karsh, Bill 80 15. Darrah, Dave 31

6. Stenger, Allen 65 16. Landry, Larry 29

7. Riha, Stepan 51 17. Elwertowski, Tom 24

8. Cutts, Kevin 50 18. Lee, Johnny 22

9. Goebel, James 49 19. Noll, Robert 22

10. Nepsund, Ronald 47

There are three ways to earn points: (1) scoring in the top 5 of any Challenge, (2) being the first person to find a bug in a published winning solution or, (3) being the first person to suggest a Challenge that I use. The points you can win are:

1st place 20 points 5th place 2 points

2nd place 10 points finding bug 2 points

3rd place 7 points suggesting Challenge 2 points

4th place 4 points

Here is Gustav’s winning solution:

Find Again and Again

Copyright © 1995 Gustav Larsson

Constants & Types
#define ALPHABET_SIZE 256
#define ALLOC_SIZE(n) ((n+3) & -4L) /* next multiple of 4 */
#define HASH_BUCKETS 1024           /* must be power of 2 */
#define HASH_MASK (HASH_BUCKETS - 1)
#define NO_NULL_CHAR 'A'
#define NULL 0

typedef unsigned char  uchar;
typedef unsigned short ushort;
typedef unsigned long  ulong;

typedef struct Word Word;
typedef struct Occurrence Occurrence;
typedef struct Private Private;

/* 
  A block of occurrence positions.  We pack in as many occurrences as possible into 
  a single block, from 3 to 6 depending on textLength.

  The first entry in the block is always used.  The remaining entries are in use if they 
  are not zero.  These facts are used several places to simplify the code.
*/
struct Occurrence {
  Occurrence *next;
  union {
    ushort pos2[6];   /* 2 bytes/occurrence */
    struct {
      ushort lo[4];
      uchar  hi[4];
    } pos3;           /* 3 bytes/occurrence */
    long pos4[3];     /* 4 bytes/occurrence */
  } p;
};

/*
  There is one Word struct for each distinct word.  The word’s length is stored in the 
  top eight bits of the hash value.  There’s no need to store the characters in the word 
  since we can just look at the first occurrence (first entry in Word.first).
*/
struct Word {
  Word        *next;
  ulong       hash;
  Occurrence  *last;
  Occurrence  first;
};

/*
  The structure of our private storage.  The hashCodes[] array serves two purposes: it 
  distinguishes alphanumeric from non-alphanumeric characters, and it provides a 
  non-zero hash code for each alphanumeric character.  The endParsedText field will 
  be -1 if there was enough private memory to parse all the text.  Otherwise, it points to 
  the start of the unparsed text.  nullChar is used by the BMH_Search() function when 
  we must search unparsed text for an occurrence.
*/
struct Private {
  ulong hashCodes [ ALPHABET_SIZE ];
  Word  *hashTable [ HASH_BUCKETS ];
  long  endParsedText;  /* start of parsed text */
  long  posBytes;       /* POS_x_BYTES, below */
  char  nullChar;       /* char not appearing in the text */
  long  heap;           /* start of private heap  */
};

Macros
/*
  These macros simplify access to the occurrence positions stored in an Occurrence 
  struct.  Posbytes is a macro argument that is usually set to private->posBytes.  
  However, you can also use a constant for posbytes, which lets the compiler choose 
  the right case at compile time, producing smaller and faster code.
*/
#define POS_2_BYTES 1   /* word position fits in 2 bytes */
#define POS_3_BYTES 0   /* fits in 3 bytes; usual case */
#define POS_4_BYTES 2   /* fits in 4 bytes */

#define GET_POS(pos,occur,index,posbytes)           \
  {                                                 \
    if ( (posbytes) == POS_3_BYTES )                \
      pos = ((long)(occur)->p.pos3.hi[index] << 16) \
          + (occur)->p.pos3.lo[index];              \
    else if ( (posbytes) == POS_2_BYTES )           \
      pos = (occur)->p.pos2[index];                 \
    else                                            \
      pos = (occur)->p.pos4[index];                 \
  }

#define SET_POS(pos,occur,index,posbytes)       \
  {                                             \
    if ( (posbytes) == POS_3_BYTES )            \
    {                                           \
      (occur)->p.pos3.hi[index] = (pos) >> 16;  \
      (occur)->p.pos3.lo[index] = (pos);        \
    }                                           \
    else if ( (posbytes) == POS_2_BYTES )       \
      (occur)->p.pos2[index] = pos;             \
    else                                        \
      (occur)->p.pos4[index] = pos;             \
  }

InitFind
void InitFind (
  char *textToSearch,
  long textLength,
  void *privateStorage,
  long storageSize
)
{
  Private *private = privateStorage;

  private->endParsedText =
    InitFindBody(
        (uchar *)textToSearch,
        textLength,
        privateStorage,
        (uchar *)privateStorage + storageSize
    );

  if ( private->endParsedText != -1 )
    private->nullChar =
      PickNullChar(
            private,
            (uchar *)textToSearch + private->endParsedText,
            (uchar *)textToSearch + textLength );
  else
    private->nullChar = NO_NULL_CHAR;
}

InitFindBody
/*
  This function does most of the work for InitFind().  The arguments have been recast 
  into a more useful form; uchar and ulong are used a lot so that we don’t have to 
  worry about the sign, especially when indexing private->hashCodes[].

  The return value is the character position when the unparsed text begins (if we run 
  out of private storage), or -1 if all the text was parsed.
*/
static long InitFindBody (
  uchar   *textToSearch,
  long    textLength,
  Private *private,
  uchar   *endPrivateStorage
)
{
  uchar       *alloc, *textPos, *textEnd, *wordStart;
  long        wordLength;
  ulong       hash, code;
  Word        *word;
  Occurrence  *occur;

/*
  Init table of hash codes.  The remaining entries are guaranteed to be initialized to 
  zero.  The hash codes were chosen so that any two codes differ by at least five bits.
  */
  {
    ulong *table = private->hashCodes;  /* reduces typing */

    table['0'] = 0xFFC0;  table['5'] = 0xF492;
    table['1'] = 0xFE07;  table['6'] = 0xF31E;
    table['2'] = 0xF98B;  table['7'] = 0xF2D9;
    table['3'] = 0xF84C;  table['8'] = 0xCF96;
    table['4'] = 0xF555;  table['9'] = 0xCE51;

    table['A'] = 0xC9DD;  table['N'] = 0xA245;
    table['B'] = 0xC81A;  table['O'] = 0x9F0A;
    table['C'] = 0xC503;  table['P'] = 0x9ECD;
    table['D'] = 0xC4C4;  table['Q'] = 0x9941;
    table['E'] = 0xC348;  table['R'] = 0x9886;
    table['F'] = 0xC28F;  table['S'] = 0x959F;
    table['G'] = 0xAF5C;  table['T'] = 0x9458;
    table['H'] = 0xAE9B;  table['U'] = 0x93D4;
    table['I'] = 0xA917;  table['V'] = 0x9213;
    table['J'] = 0xA8D0;  table['W'] = 0x6DD3;
    table['K'] = 0xA5C9;  table['X'] = 0x6C14;
    table['L'] = 0xA40E;  table['Y'] = 0x6B98;
    table['M'] = 0xA382;  table['Z'] = 0x6A5F;

    table['a'] = 0x6746;  table['n'] = 0x3C88;
    table['b'] = 0x6681;  table['o'] = 0x3B04;
    table['c'] = 0x610D;  table['p'] = 0x3AC3;
    table['d'] = 0x60CA;  table['q'] = 0x37DA;
    table['e'] = 0x5D85;  table['r'] = 0x361D;
    table['f'] = 0x5C42;  table['s'] = 0x3191;
    table['g'] = 0x5BCE;  table['t'] = 0x3056;
    table['h'] = 0x5A09;  table['u'] = 0x0D19;
    table['i'] = 0x5710;  table['v'] = 0x0CDE;
    table['j'] = 0x56D7;  table['w'] = 0x0B52;
    table['k'] = 0x515B;  table['x'] = 0x0A95;
    table['l'] = 0x509C;  table['y'] = 0x078C;
    table['m'] = 0x3D4F;  table['z'] = 0x064B;
  }

  /*  Determine the number of bytes needed to store each occurrence position. */
  if ( textLength <= 0x10000L )
    private->posBytes = POS_2_BYTES;
  else if ( textLength <= 0x1000000L )
    private->posBytes = POS_3_BYTES;
  else
    private->posBytes = POS_4_BYTES;

  /* Set up variables to handle allocation of private storage. */
  alloc = (uchar *)&private->heap;

  /* Parse the text */
  textPos = textToSearch;
  textEnd = textPos + textLength;

  while ( textPos != textEnd )
  {
    /* Search for start of word */
    while ( private->hashCodes[*textPos] == 0 )
    {
      textPos++;
      if ( textPos == textEnd )
        return -1;  /* parse all text */
    }
    wordStart = textPos;

    /* Search for end of word; generate hash value too */
    hash = 0;
    while ( textPos != textEnd &&
            (code = private->hashCodes[ *textPos ]) != 0 )
    {
      hash = (hash << 1) ^ code;
      textPos++;
    }
    wordLength = textPos - wordStart;
    hash = (hash & 0xFFFFFF) | (wordLength << 24);

    /*
      Record the occurrence.  First we see if a Word struct exists for this word and 
      whether we need to allocate a new Occurrence struct.
    */
    word = LookupWord(
                private,
                (char *)textToSearch,
                (char *)wordStart,
                wordLength,
                hash );
    if ( word )
    {
      long allocateNewBlock, blockSize, i, pos;

      /*
        This word has occurred before, so it already has a Word struct.  See if there’s 
        room in the last Occurrence block for another entry.  Remember that entry #0 in 
        the Occurrence block is always in use, so we can start checking at entry #1 for a 
        non-zero entry.
      */
      occur = word->last;
      allocateNewBlock = TRUE;
      switch ( private->posBytes )
      {
        case POS_2_BYTES:  blockSize = 6; break;
        case POS_3_BYTES:  blockSize = 4; break;
        case POS_4_BYTES:  blockSize = 3; break;
      }

      for ( i = 1; i < blockSize; i++ )
      {
        GET_POS( pos, occur, i, private->posBytes )
        if ( pos == 0 )
        {
          SET_POS( wordStart - textToSearch, occur, i,
                   private->posBytes )
          allocateNewBlock = FALSE;
          break;
        }
      }

      if ( allocateNewBlock )
      {
        /* Block is full.  Allocate new Occurrence block */
        occur = (Occurrence *) alloc;
        alloc += ALLOC_SIZE( sizeof(Occurrence) );
        if ( alloc >= endPrivateStorage )
          return wordStart-textToSearch; /* out of memory */

        /* Init the new struct and link it to the end of the occurence list. */
        SET_POS( wordStart - textToSearch, occur, 0,
                 private->posBytes )
        word->last->next = occur;
        word->last = occur;
      }
    }
    else
    {
      long i;

/* This is a new word.  Allocate a new Word struct, which contains an Occurrence 
    struct too.  */
      word = (Word *) alloc;
      alloc += ALLOC_SIZE( sizeof(Word) );
      if ( alloc >= endPrivateStorage )
        return wordStart-textToSearch ;  /* out of memory */

      /*  Link it to the start of the Word list, coming off the hash table. */
      word->next = private->hashTable[ hash & HASH_MASK ];
      private->hashTable[ hash & HASH_MASK ] = word;

      /* Init the Word struct */
      word->hash = hash;
      word->last = &word->first;

      /* Init the Occurrence struct */
      SET_POS( wordStart - textToSearch, &word->first, 0,
               private->posBytes )
    }
  }

  /* Finished parsing text */
  return -1;
}

FindWordOccurrence
long FindWordOccurrence (
  char *wordToFind,
  long wordLength,
  long occurrenceToFind,
  char *textToSearch,
  long textLength,
  void *privateStorage,
  long storageSize
)
{
  Private *private = privateStorage;
  Word  *word;
  ulong hash;

  /* Make occurenceToFind zero-based */
  occurrenceToFind--;

  /* Generate hash value for word to find */
  hash = 0;
  {
    long remain = wordLength;
    uchar *p = (uchar *) wordToFind;
    while ( remain > 0 )
    {
      hash = (hash << 1) ^ private->hashCodes[*p++];
      remain--;
    }
    hash = (hash & 0xFFFFFF) | (wordLength << 24);
  }

  /* Look for word/occurrence in hash table */
  word = LookupWord( private, textToSearch, wordToFind,
                     wordLength, hash );
  if ( word )
  {
    Occurrence *occur = &word->first;
    long blockSize, pos, i;

    /* Word exists in hash table, so go down the occurrence list.  */
    switch ( private->posBytes )
    {
      case POS_2_BYTES: blockSize = 6;  break;
      case POS_3_BYTES: blockSize = 4;  break;
      case POS_4_BYTES: blockSize = 3;  break;
    }

    while ( occur && occurrenceToFind >= blockSize )
    {
      occurrenceToFind -= blockSize;
      occur = occur->next;
    }

    if ( occur )
    {
      GET_POS( pos, occur, occurrenceToFind,
               private->posBytes )
      if ( occurrenceToFind == 0 || pos != 0 )
        return pos;
      occurrenceToFind -= blockSize;
    }

    occur = word->last;
    for ( i = 0; i < blockSize; i++ )
    {
      GET_POS( pos, occur, i, private->posBytes )
      if ( pos == 0 )
        occurrenceToFind++;
    }
  }

  /* Not in parsed text, so check the unparsed text */
  if ( private->endParsedText != -1 )
  {
    char *p;
    if ( wordLength > 3 )
      p = BMH_Search(
              private->hashCodes,
              wordToFind,
              wordLength,
              occurrenceToFind,
              textToSearch + private->endParsedText,
              textToSearch + textLength,
              private->nullChar );
    else
      p = SimpleSearch(
              private->hashCodes,
              wordToFind,
              wordLength,
              occurrenceToFind,
              textToSearch + private->endParsedText,
              textToSearch + textLength );
    if (p)
      return (p - textToSearch);
  }

  /* Not found */
  return -1;
}

LookupWord 
/* Look up a word in the hash table */
static Word *LookupWord (
  Private *private,
  char    *textToSearch,
  char    *wordText,
  long    wordLength,
  ulong   hash
)
{
  Word *word = private->hashTable[ hash & HASH_MASK ];
  while ( word )
  {
    if ( word->hash == hash )
    {
      char *w1, *w2;
      long pos, remain = wordLength;

      /*
        The hash values match, so compare characters to make sure it’s the right word.  
        We already know the word length is correct since the length is contained
        in the upper eight bits of the hash value.
      */
      GET_POS( pos, &word->first, 0, private->posBytes )
      w1 = textToSearch + pos;
      w2 = wordText;
      while ( remain-- > 0 && *w1++ == *w2++ )
        ;
      if ( remain == -1 )
        return word;
    }
    word = word->next;
  }
  return NULL;
}

PickNullChar 
/*
  Find a character that doesn’t appear anywhere in the unparsed text.  BMH_Search() is 
  faster if such a character can be found.
*/
static char PickNullChar (
  Private *private,
  uchar   *textStart,
  uchar   *textEnd
)
{
  long i;
  uchar *p, occurs[ ALPHABET_SIZE ];

  for ( i = 0; i < ALPHABET_SIZE; i++ )
    occurs[i] = FALSE;

  for ( p = textStart; p < textEnd; p++ )
    occurs[*p] = TRUE;

  for ( i = 0; i < ALPHABET_SIZE; i++ )
    if ( occurs[i] == FALSE && private->hashCodes[i] == 0 )
      return i;

  return NO_NULL_CHAR;
}

BMH_Search
/*
  Search the unparsed text using the Boyer-Moore-Horspool algorithm.  Ideally a null 
  character is supplied (one that appears in neither the search string nor the text being 
  searched).  This allows the inner loop to be faster.
*/
static char *BMH_Search (
  ulong *hashCodes,       /* private->hashCodes     */
  char  *wordToFind,
  long  wordLength,
  long  occurrenceToFind, /* 0 is first occurrence  */
  char  *textStart,       /* start of unparsed text */
  char  *textEnd,         /* end of unparsed text   */
  char  nullChar          /* private->nullChar      */
)
{
  long  i;
  char  *text, *wordEnd;
  char  word[256];
  long  offset[ ALPHABET_SIZE ];

  /*
    Copy the search string to a private buffer, where
    the first character is the null character.
  */
  word[0] = nullChar;
  for ( i = 0; i < wordLength; i++ )
    word[i+1] = wordToFind[i];

  /* Set up the offset[] lookup table */
  for ( i = 0; i < ALPHABET_SIZE; i++ )
    offset[i] = wordLength;

  for ( i = 1; i < wordLength; i++ )
    offset[ word[i] ] = wordLength - i;

  /* Let the search begin... */
  wordEnd = word + wordLength;
  text = textStart + wordLength - 1;

  if ( nullChar == NO_NULL_CHAR )
  {
    /* No null character, so use a slower inner loop */
    while ( text < textEnd )
    {
      long i;
      char *p, *q;
      for ( i = wordLength, p = wordEnd, q = text;
            i > 0 && *p == *q;
            i--, p--, q-- )
        ;
/*If i == 0, we have found the search string.  Now we make sure that it is delimited.*/
      if ( i == 0 && hashCodes[*q] == 0 &&
           (text+1 == textEnd || hashCodes[text[1]] == 0) )
      {
        if ( occurrenceToFind == 0 )
          return q+1;
        occurrenceToFind--;
      }

      text += offset[*text];
    }
  }
  else
  {
    /* There is a null character (usual case), 
        so we can use a faster and simpler inner loop. */
    while ( text < textEnd )
    {
      char *p, *q;
      for ( p = wordEnd, q = text; *p == *q; p--, q-- )
        ;
      if ( p == word && hashCodes[*q] == 0 &&
           (text+1 == textEnd || hashCodes[text[1]] == 0) )
      {
        if ( occurrenceToFind == 0 )
          return q+1;
        occurrenceToFind--;
      }
      text += offset[*text];
    }
  }
  return NULL;
}

SimpleSearch
/*
  Search the unparsed text using a simple search algorithm.  Note that wordLength 
  must be 1, 2, or 3.  This algorithm runs faster than BMH_Search() for small search 
  strings.
*/
static char *SimpleSearch(
  ulong *hashCodes,       /* private->hashCodes      */
  char  *wordToFind,
  long  wordLength,       /* 1..3                    */
  long  occurrenceToFind, /* 0 is 1st occurrence     */
  char  *textStart,       /* start of unparsed text  */
  char  *textEnd          /* end of all text         */
)
{
  char *text, first;

  first = wordToFind[0];
  text = textStart;

  if ( wordLength == 1 )
  {
    while ( text < textEnd )
    {
      while ( text < textEnd && *text != first )
        text++;
      if ( hashCodes[*(text-1)] == 0 &&
           hashCodes[text[wordLength]] == 0 )
      {
        if ( occurrenceToFind == 0 )
          return text;
        occurrenceToFind--;
      }
    text++;
    }
  }
  else if ( wordLength == 2 )
  {
    while ( text < textEnd )
    {
      while ( text < textEnd && *text != first )
        text++;
      if ( text[1] == wordToFind[1] &&
           hashCodes[*(text-1)] == 0 &&
           hashCodes[text[wordLength]] == 0 )
      {
        if ( occurrenceToFind == 0 )
          return text;
        occurrenceToFind--;
      }
    text++;
    }
  }
  else /* wordLength == 3 */
  {
    while ( text < textEnd )
    {
      while ( text < textEnd && *text != first )
        text++;
      if ( text[1] == wordToFind[1] &&
           text[2] == wordToFind[2] &&
           hashCodes[*(text-1)] == 0 &&
           hashCodes[text[wordLength]] == 0 )
      {
        if ( occurrenceToFind == 0 )
          return text;
        occurrenceToFind--;
      }
    text++;
    }
  }
  return NULL;
}

 

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NeoFinder (formerly CDFinder) rapidly organizes your data, either on external or internal disks, or any other volumes. It catalogs and manages all your data, so you stay in control of your data... Read more
App Tamer 2.5 - Efficiently manage your...
App Tamer tames your processor-monopolizing apps and keeps them from chewing up excessive CPU time and battery life. Powered by a unique AutoStop feature, App Tamer stops each application when you... Read more
MainStage 3 3.4.4 - Live performance too...
Apple MainStage makes it easy to bring to the stage all the same instruments and effects that you love in your recording. Everything from the Sound Library and Smart Controls you're familiar with... Read more
iTubeDownloader 6.5.13 - Easily download...
iTubeDownloader is a powerful-yet-simple YouTube downloader for the masses. Because it contains a proprietary browser, you can browse YouTube like you normally would. When you see something you want... Read more
FileZilla 3.47.0 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.47.0: Fixed regression loading advanced site... Read more
Transmit 5.6.3 - Excellent FTP/SFTP clie...
Transmit is an excellent FTP (file transfer protocol), SFTP, S3 (Amazon.com file hosting) and iDisk/WebDAV client that allows you to upload, download, and delete files over the internet. With the... Read more
Doomsday 2.2.2 - Play classic Doom on mo...
id Software's Doom pioneered the modern first-person shooter genre. Released in 1993, it was a quantum leap in game engine technology with fluid and - at the time - incredibly realistic 3D graphics.... Read more
Ableton Live 10.1.9 - Record music using...
Ableton Live lets you create and record music on your Mac. Use digital instruments, pre-recorded sounds, and sampled loops to arrange, produce, and perform your music like never before. Ableton Live... Read more
Maintenance 2.6.5 - System maintenance u...
Maintenance is a system maintenance and cleaning utility. It allows you to run miscellaneous tasks of system maintenance: Check the the structure of the disk Repair permissions Run periodic scripts... Read more

Latest Forum Discussions

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Creepy Little Monsters is a cute, monste...
Creepy Little Monsters is a retro throwback that sees you traversing tricky puzzle-platformer levels as a one-eyed monster. It aims to offer a fresh take on 80s and 90s classics of the genre, and it's out right now for iOS and Android. [Read more... | Read more »
Tyrant's Arena delivers intense her...
Tyrant's Arena is an intense midcore multiplayer actioner where you'll compete in tricky 3v3 matches to crush your opponents and earn neat rewards. It comes to us from developer Kroy Games, and it's now available for pre-registration on iOS and... | Read more »
Mobile Games Starter Kit
Over here at 148Apps, we regularly dive deep into the latest and greatest mobile games hitting the App Store, but that’s not always what people are looking for when searching for a new mobile game. Some folks just want to dip their toes into... | Read more »
Unresolved is a hard-hitting narrative a...
Ghofran Akil's Unresolved in an upcoming text-based adventure game that sees you playing as a mother attempting to find her disappeared husband during the Lebanese Civil War. [Read more] | Read more »
Marvel Strike Force introduces new brawl...
FoxNext's squad-based RPG Marvel Strike Force is set to receive some fresh characters from the X-Men and Iron Man series. They'll arrive as part of the game's latest update, which follows a sizable spending boycott on the title due to complaints... | Read more »
Speed Dating for Ghosts is a narrative a...
Speed Dating for Ghosts originally released on Steam back 2018, since then it has received honourable mentions for narrative during the Independent Games Festival. Now it's made its way over to iOS devices where it's available as a premium title... | Read more »
Fast-paced multiplayer title Tennis Star...
Tennis Stars: Ultimate Clash is the latest free-to-play tennis title to hit iOS and Android. It's said to be a fairly casual experience, offering easy-to-learn controls and fast-paced, mobile-friendly matches. [Read more] | Read more »
Super Mecha Champions' latest updat...
Super Mecha Champions' latest update sees the addition of a brand new character called R.E.D. Alongside that, there's news about the current season and a series of Emojis that have been added to the game. [Read more] | Read more »
Apple Arcade: Ranked - Top 50 [Updated 2...
In case you missed it, I am on a quest to rank every Apple Arcade game there is. [Read more] | Read more »
Apple Arcade: Ranked - 51+ [Updated 2.19...
This is part 2 of our Apple Arcade Ranking list. To see part 1, go here. To skip to part 3, click here. 51. Mini Motorways Description: [Read more] | Read more »

Price Scanner via MacPrices.net

B&H is again offering $100 discounts on M...
B&H Photo has 4-Core and 6-Core Mac minis on sale for $100 off Apple’s standard MSRP, with prices starting at only $699. Overnight shipping is free to many US addresses: – 3.6GHz Quad-Core mini... Read more
B&H Photo drops iMac prices, offers model...
B&H Photo has new 2019 21″ and 27″ 5K iMacs in stock today and on sale for up to $250 off Apple’s MSRP, with prices starting at only $999. These are the same iMacs sold by Apple in their retail... Read more
Flash sale! 11″ 64GB WiFi iPad Pro for $674,...
Walmart has the 11″ 64GB WiFi iPad Pro on sale on their online store today for $674. That’s $125 off Apple’s MSRP for this model and the cheapest price available from any Apple reseller. Choose free... Read more
Sale! Get the 256GB 13″ Silver MacBook Air fo...
Amazon has new 2019 13″ 1.6GHz/256GB MacBook Airs, in Silver, on sale today for only $999 shipped. Their price is $300 off Apple’s MSRP for this model, and it’s the cheapest price for a 256GB MacBook... Read more
Verizon offers free iPhone 7 to customers ope...
Verizon is offering a free 32GB iPhone 7 for new or existing customers who open a new line of service, no trade-in required. Cost of the phone is credited to your account monthly over 24 months. The... Read more
Sale! 10.5″ 256GB WiFi iPad Air for $549, $10...
Amazon has new 10.5″ 256GB WiFi iPad Airs, in Space Gray, on sale today for $549 shipped. Their price is $100 off Apple’s MSRP for this model, and it’s the cheapest price available from any Apple... Read more
Back on sale! Apple’s new Mac Pro for $5499,...
B&H Photo has the base 2019 Mac Pro (3.5GHz 8-Core Xeon, 32GB RAM, 256GB SSD) in stock today and on sale for $5499 including free overnight delivery to many addresses in the US. Their price is $... Read more
B&H offers $100 discount on base 13″ 1.4G...
B&H Photo has new 2019 13″ 1.4GHz MacBook Pros on sale for $100 off Apple’s MSRP today with prices starting at $1199. Overnight shipping is free to many addresses in the US. These are the same... Read more
Apple continues to offer Certified Refurbishe...
Apple has Certified Refurbished iPhone XS models available for up to $350 off MSRP, with prices starting at $699. Each iPhone is unlocked and comes with Apple’s standard one-year warranty and a new... Read more
Apple AirPods are on sale for $30 off today
Amazon has new 2019 Apple AirPods (non-Pro models) on sale today for $30 off MSRP, starting at $129. Shipping is free: – AirPods with Wireless Charging Case: $169 $30 off MSRP – AirPods with Charging... Read more

Jobs Board

Medical Assistant - *Apple* Valley Clinic -...
…professional, quality care to patients in the ambulatory setting at the M Health Fairview Apple Valley Clinic, located in Apple Valley, MN. Join the **M Health Read more
Geek Squad Advanced Repair *Apple* Professi...
**764652BR** **Job Title:** Geek Squad Advanced Repair Apple Professional **Job Category:** Store Associates **Store NUmber or Department:** 000245- Apple Read more
Medical Assistant - *Apple* Valley Clinic -...
…professional, quality care to patients in the ambulatory setting at the M Health Fairview Apple Valley Clinic, located in Apple Valley, MN. Join the **M Health Read more
Windows/ *Apple* Technical Support Engineer...
Windows/ Apple Technical Support Engineer McLean , VA , US Apply + Be you + Be Booz Allen + Be empowered + Learn More Job Description Location: McLean, VA, US Job Read more
Medical Assistant - *Apple* Valley Clinic -...
…professional, quality care to patients in the ambulatory setting at the M Health Fairview Apple Valley Clinic, located in Apple Valley, MN. Join the **M Health Read more
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