折半查找

- (void)viewDidLoad {
   [super viewDidLoad];

   int number[10] = {1,2,3,4,5,6,7,8,9,10};
   int num = (int)sizeof(number) / sizeof(int);
   int snum = 7;
   [self search:number min:0 max:num searchNum:snum];

}

// 递归调用
- (void)search:(int *)number min:(int)min max:(int)max searchNum:(int)snum {

    int mid = (min + max) / 2;
     if (number[mid] == snum ) {
         NSLog(@"%d",mid);
     }else if (number[mid] > snum) {
         max = mid-1;
        [self search:number min:min max:max searchNum:snum];
     }else if (number[mid] < snum) {
         min = mid+1;
         [self search:number min:min max:max searchNum:snum];
   }

}