BinarySearch.m

BinarySearch.m

//
//  BinarySearch.m
//  KIObjcAlgorithms
//
//  Created by Keita on 9/8/15.
//  Copyright (c) 2015 Keita Ito. All rights reserved.
//

#import "BinarySearch.h"

@implementation BinarySearch

- (NSInteger)binarySearch:(NSArray *)array targetNumber:(NSUInteger)target {
    
    NSUInteger minIndex = 0;
    NSUInteger maxIndex = array.count - 1;
    NSUInteger midIndex = 0;
    
    while (minIndex <= maxIndex) {
        NSLog(@"minIndex: %ld (%@) maxIndex: %ld (%@)", minIndex, array[minIndex], maxIndex, array[maxIndex]);
        midIndex = (minIndex + maxIndex) / 2;
        NSLog(@"midIndex is now %ld (%@)", midIndex, array[midIndex]);
        
        if ([[array objectAtIndex:midIndex] integerValue] == target) {
            NSLog(@"target index is %ld", midIndex);
            return midIndex;
        }
        else if ([[array objectAtIndex:midIndex] integerValue] < target) {
            minIndex = midIndex + 1;
        }
        else if ([[array objectAtIndex:midIndex] integerValue] > target) {
            maxIndex = midIndex - 1;
        }
    }
    
    NSLog(@"Target is not found");
    return -1;
}

@end