langs a-z

Task/Binary-search/Objective-C/binary-search-1.m

@@ -0,0 +1,51 @@
+#import <Foundation/Foundation.h>
+
+@interface NSArray (BinarySearch)
+// Requires all elements of this array to implement a -compare: method which
+// returns a NSComparisonResult for comparison.
+// Returns NSNotFound when not found
+- (NSInteger) binarySearch:(id)key;
+@end
+
+@implementation NSArray (BinarySearch)
+- (NSInteger) binarySearch:(id)key {
+  NSInteger lo = 0;
+  NSInteger hi = [self count] - 1;
+  while (lo <= hi) {
+    NSInteger mid = lo + (hi - lo) / 2;
+    id midVal = [self objectAtIndex:mid];
+    switch ([midVal compare:key]) {
+    case NSOrderedAscending:
+      lo = mid + 1;
+      break;
+    case NSOrderedDescending:
+      hi = mid - 1;
+      break;
+    case NSOrderedSame:
+      return mid;
+    }
+  }
+  return NSNotFound;
+}
+@end
+
+int main()
+{
+  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+
+  NSArray *a = [NSArray arrayWithObjects:
+		   [NSNumber numberWithInt: 1],
+		   [NSNumber numberWithInt: 3],
+		   [NSNumber numberWithInt: 4],
+		   [NSNumber numberWithInt: 5],
+		   [NSNumber numberWithInt: 6],
+		   [NSNumber numberWithInt: 7],
+		   [NSNumber numberWithInt: 8],
+		   [NSNumber numberWithInt: 9],
+		   [NSNumber numberWithInt: 10],
+		   nil];
+  NSLog(@"6 is at position %d", [a binarySearch:[NSNumber numberWithInt: 6]]); // prints 4
+
+  [pool drain];
+  return 0;
+}

Task/Binary-search/Objective-C/binary-search-2.m

@@ -0,0 +1,49 @@
+#import <Foundation/Foundation.h>
+
+@interface NSArray (BinarySearchRecursive)
+// Requires all elements of this array to implement a -compare: method which
+// returns a NSComparisonResult for comparison.
+// Returns NSNotFound when not found
+- (NSInteger) binarySearch:(id)key inRange:(NSRange)range;
+@end
+
+@implementation NSArray (BinarySearchRecursive)
+- (NSInteger) binarySearch:(id)key inRange:(NSRange)range {
+  if (range.length == 0)
+    return NSNotFound;
+  NSInteger mid = range.location + range.length / 2;
+  id midVal = [self objectAtIndex:mid];
+  switch ([midVal compare:key]) {
+  case NSOrderedAscending:
+    return [self binarySearch:key
+                      inRange:NSMakeRange(mid + 1, NSMaxRange(range) - (mid + 1))];
+  case NSOrderedDescending:
+    return [self binarySearch:key
+                      inRange:NSMakeRange(range.location, mid - range.location)];
+  default:
+    return mid;
+  }
+}
+@end
+
+int main()
+{
+  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+
+  NSArray *a = [NSArray arrayWithObjects:
+		   [NSNumber numberWithInt: 1],
+		   [NSNumber numberWithInt: 3],
+		   [NSNumber numberWithInt: 4],
+		   [NSNumber numberWithInt: 5],
+		   [NSNumber numberWithInt: 6],
+		   [NSNumber numberWithInt: 7],
+		   [NSNumber numberWithInt: 8],
+		   [NSNumber numberWithInt: 9],
+		   [NSNumber numberWithInt: 10],
+		   nil];
+  NSLog(@"6 is at position %d", [a binarySearch:[NSNumber numberWithInt: 6]
+                                        inRange:NSMakeRange(0, [a count])]); // prints 4
+
+  [pool drain];
+  return 0;
+}

Task/Binary-search/Objective-C/binary-search-3.m

@@ -0,0 +1,25 @@
+#import <Foundation/Foundation.h>
+
+int main()
+{
+  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+
+  NSArray *a = [NSArray arrayWithObjects:
+		   [NSNumber numberWithInt: 1],
+		   [NSNumber numberWithInt: 3],
+		   [NSNumber numberWithInt: 4],
+		   [NSNumber numberWithInt: 5],
+		   [NSNumber numberWithInt: 6],
+		   [NSNumber numberWithInt: 7],
+		   [NSNumber numberWithInt: 8],
+		   [NSNumber numberWithInt: 9],
+		   [NSNumber numberWithInt: 10],
+		   nil];
+  NSLog(@"6 is at position %lu", [a indexOfObject:[NSNumber numberWithInt: 6]
+                                    inSortedRange:NSMakeRange(0, [a count])
+                                          options:0
+                                  usingComparator:^(id x, id y){ return [x compare: y]; }]); // prints 4
+
+  [pool drain];
+  return 0;
+}

Task/Binary-search/Objective-C/binary-search-4.m

@@ -0,0 +1,30 @@
+#import <Foundation/Foundation.h>
+
+CFComparisonResult myComparator(const void *x, const void *y, void *context) {
+  return [(id)x compare:(id)y];
+}
+
+int main()
+{
+  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+
+  NSArray *a = [NSArray arrayWithObjects:
+		   [NSNumber numberWithInt: 1],
+		   [NSNumber numberWithInt: 3],
+		   [NSNumber numberWithInt: 4],
+		   [NSNumber numberWithInt: 5],
+		   [NSNumber numberWithInt: 6],
+		   [NSNumber numberWithInt: 7],
+		   [NSNumber numberWithInt: 8],
+		   [NSNumber numberWithInt: 9],
+		   [NSNumber numberWithInt: 10],
+		   nil];
+  NSLog(@"6 is at position %d", CFArrayBSearchValues((CFArrayRef)a,
+                                                     CFRangeMake(0, [a count]),
+                                                     [NSNumber numberWithInt: 6],
+                                                     myComparator,
+                                                     NULL)); // prints 4
+
+  [pool drain];
+  return 0;
+}