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| Original file line number | Diff line number | Diff line change |
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| #import <Foundation/Foundation.h> | ||
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| #ifdef __cplusplus | ||
| extern "C" { | ||
| #endif | ||
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| /** | ||
| * Calculates the Levenshtein distance between two strings using the Wagner-Fischer algorithm. | ||
| * | ||
| * @param s1 | ||
| * @param s2 | ||
| * @return The Levenshtein distance between s1 and s2. | ||
| */ | ||
| NSInteger levenshteinDistance(NSString *s1, NSString *s2); | ||
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| /** | ||
| * Calculates the Levenshtein distances for every pairing of words in the given array. | ||
| * | ||
| * @param words | ||
| * @return A pointer to an array of NSInteger values representing the distances. | ||
| */ | ||
| NSInteger* distances(NSArray<NSString *> *words); | ||
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| #ifdef __cplusplus | ||
| } | ||
| #endif |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,92 @@ | ||
| #import <Foundation/Foundation.h> | ||
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| /** | ||
| * Calculates the Levenshtein distance between two strings using Wagner-Fischer algorithm | ||
| * Space Complexity: O(min(m,n)) - only uses two arrays instead of full matrix | ||
| * Time Complexity: O(m*n) where m and n are the lengths of the input strings | ||
| */ | ||
| NSInteger levenshteinDistance(NSString *s1, NSString *s2) { | ||
| // Early termination checks | ||
| if ([s1 isEqualToString:s2]) return 0; | ||
| if (s1.length == 0) return s2.length; | ||
| if (s2.length == 0) return s1.length; | ||
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| // Make s1 the shorter string for space optimization | ||
| if (s1.length > s2.length) { | ||
| NSString *temp = s1; | ||
| s1 = s2; | ||
| s2 = temp; | ||
| } | ||
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| NSUInteger m = s1.length; | ||
| NSUInteger n = s2.length; | ||
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| // Use two arrays instead of full matrix for space optimization | ||
| NSMutableData *prevRowData = [NSMutableData dataWithLength:(m + 1) * sizeof(NSInteger)]; | ||
| NSMutableData *currRowData = [NSMutableData dataWithLength:(m + 1) * sizeof(NSInteger)]; | ||
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| NSInteger *prevRow = (NSInteger *)prevRowData.mutableBytes; | ||
| NSInteger *currRow = (NSInteger *)currRowData.mutableBytes; | ||
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| // Initialize first row | ||
| for (NSUInteger i = 0; i <= m; i++) { | ||
| prevRow[i] = (NSInteger)i; | ||
| } | ||
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| // Convert strings to UTF-16 for faster access | ||
| const unichar *s1Chars = CFStringGetCharactersPtr((__bridge CFStringRef)s1); | ||
| const unichar *s2Chars = CFStringGetCharactersPtr((__bridge CFStringRef)s2); | ||
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| NSMutableData *s1Buffer = nil; | ||
| NSMutableData *s2Buffer = nil; | ||
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| // If direct access failed, create buffers | ||
| if (s1Chars == NULL) { | ||
| s1Buffer = [NSMutableData dataWithLength:m * sizeof(unichar)]; | ||
| s1Chars = s1Buffer.mutableBytes; | ||
| [s1 getCharacters:(unichar *)s1Chars range:NSMakeRange(0, m)]; | ||
| } | ||
| if (s2Chars == NULL) { | ||
| s2Buffer = [NSMutableData dataWithLength:n * sizeof(unichar)]; | ||
| s2Chars = s2Buffer.mutableBytes; | ||
| [s2 getCharacters:(unichar *)s2Chars range:NSMakeRange(0, n)]; | ||
| } | ||
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| // Main computation loop | ||
| for (NSUInteger j = 1; j <= n; j++) { | ||
| currRow[0] = (NSInteger)j; | ||
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| for (NSUInteger i = 1; i <= m; i++) { | ||
| NSInteger cost = (s1Chars[i-1] == s2Chars[j-1]) ? 0 : 1; | ||
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| // Calculate minimum of three operations | ||
| NSInteger deletion = prevRow[i] + 1; | ||
| NSInteger insertion = currRow[i-1] + 1; | ||
| NSInteger substitution = prevRow[i-1] + cost; | ||
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| currRow[i] = MIN(deletion, MIN(insertion, substitution)); | ||
| } | ||
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| // Swap rows | ||
| NSInteger *temp = prevRow; | ||
| prevRow = currRow; | ||
| currRow = temp; | ||
| } | ||
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| return prevRow[m]; | ||
| } | ||
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| NSInteger* distances(NSArray<NSString *> *words) { | ||
| NSUInteger count = words.count * (words.count - 1); | ||
| NSInteger *result = malloc(count * sizeof(NSInteger)); | ||
| NSUInteger index = 0; | ||
| for (NSUInteger i = 0; i < words.count; i++) { | ||
| for (NSUInteger j = 0; j < words.count; j++) { | ||
| if (i < j) { | ||
| result[index] = levenshteinDistance(words[i], words[j]); | ||
| index++; | ||
| } | ||
| } | ||
| } | ||
| return result; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,85 @@ | ||
| #import <Foundation/Foundation.h> | ||
| #import "levenshtein.h" | ||
| #import "benchmark.h" | ||
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| /** | ||
| * Reads words from a file, splitting on newline characters. | ||
| * @param filePath A C-string representing the file path. | ||
| * @return An NSArray of NSString objects containing each non-empty line in the file. | ||
| */ | ||
| NSArray<NSString *> *readWords(const char *filePath) { | ||
| NSString *path = [NSString stringWithUTF8String:filePath]; | ||
| NSError *error = nil; | ||
| NSString *fileContents = [NSString stringWithContentsOfFile:path | ||
| encoding:NSUTF8StringEncoding | ||
| error:&error]; | ||
| if (!fileContents) { | ||
| NSLog(@"Error reading file %@", path); | ||
| return @[]; | ||
| } | ||
| NSArray<NSString *> *lines = [fileContents componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]]; | ||
| NSPredicate *nonEmpty = [NSPredicate predicateWithFormat:@"length > 0"]; | ||
| NSArray<NSString *> *words = [lines filteredArrayUsingPredicate:nonEmpty]; | ||
| return words; | ||
| } | ||
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| /** | ||
| * A struct to pass word data to the benchmark work function. | ||
| */ | ||
| typedef struct { | ||
| NSArray<NSString *> *words; | ||
| } word_data_t; | ||
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| /** | ||
| * The work function called by benchmark_run. | ||
| */ | ||
| static benchmark_result_t work(void *data) { | ||
| word_data_t *wd = (word_data_t *)data; | ||
| NSInteger *result = distances(wd->words); | ||
| benchmark_result_t res; | ||
| res.value.ptr = result; | ||
| return res; | ||
| } | ||
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| int main(int argc, const char * argv[]) { | ||
| @autoreleasepool { | ||
| if (argc < 4) { | ||
| NSLog(@"Usage: %s <runMs> <warmupMs> <wordsFile>", argv[0]); | ||
| return 1; | ||
| } | ||
| int runMs = atoi(argv[1]); | ||
| int warmupMs = atoi(argv[2]); | ||
| const char *wordsFilePath = argv[3]; | ||
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| NSArray<NSString *> *words = readWords(wordsFilePath); | ||
| if (!words || words.count == 0) { | ||
| NSLog(@"No words to process."); | ||
| return 1; | ||
| } | ||
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| // Set up the data for the benchmark. | ||
| word_data_t data = { words }; | ||
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| // Warmup run (result is ignored) | ||
| benchmark_run(work, &data, warmupMs); | ||
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| // Benchmark run. | ||
| benchmark_stats_t stats = benchmark_run(work, &data, runMs); | ||
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| NSInteger *distancesArray = (NSInteger *)stats.last_result.value.ptr; | ||
| // Expected count based on unique pairs (i < j) | ||
| NSUInteger count = (words.count * (words.count - 1)) / 2; | ||
| NSInteger sum = 0; | ||
| for (NSUInteger i = 0; i < count; i++) { | ||
| sum += distancesArray[i]; | ||
| } | ||
| stats.last_result.value.number = sum; | ||
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| char buffer[1024]; | ||
| benchmark_format_results(stats, buffer, sizeof(buffer)); | ||
| printf("%s\n", buffer); | ||
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| free(distancesArray); | ||
| } | ||
| return 0; | ||
| } |
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