OC各种算法,排序,查找实现

二维数组查找数字的OC实现

-(void)findNumWithNum:(NSArray<NSArray *>)num rows:(int)rows columns:(int)columns number:(int)number
{
    BOOL reuslt = false;
    int row = 0;
    int column = columns-1;
    if (rows&&columns) {
        //右上角
        while (row<rows&&columns>=0) {
            if (num[row][column]==number) {
                reuslt = true;
                break;
            }else if(num[row][column]>number){
                //del col
                column--;
            }else{
                row++;
            }
        }
    }
}

OC 二分查找的实现

- (void)viewDidLoad {
    [super viewDidLoad];
    
   NSArray * array1 = @[@1,@2,@3,@4,@5,@6,@7,@9];
    
    int result = [self compare:array1 target:@9];
    //在这里打印结果看是否有相等的值
    NSLog(@"%d",result);
}

- (int)compare:(NSArray *)array target:(int)target{
    
    if (!array.count) {
        return -1;
    }
    
   unsigned int low = 0;
   unsigned int high = array.count - 1;
    
    while (low <= high) {
        //会有一些朋友看到有些人是( low + high ) / 2这样写的,但是这样写有一点不好,就是low+high会出现整数溢出的情况,如果存在溢出,你再除以2也是没有用的,所以不能这么写
        int mid = low + ((high - low)/2);
        
        //第mid项的内容
        int num = [array objectAtIndex:mid];
        
        if (target == num) {
            return low;
        }else if (num > target){
            high = mid - 1;//左边进行查找
        }else{
            low = mid +1;//右边进行查找
        }
    }
    return -1;//返回-1是没找到
}

快速排序

-(void)quickSort:(CFArrayRef*)arr L:(int)L R:(int)R{
    int i = L;
    int j = R;
    
    
    int mid = arr[(L+R)/2];
    while (i<=j) {
        while (mid>arr[i]) {
            i++;
        }
        while (mid<=arr[j]) {
            j--;
        }
        if (i<=j) {
            int temp = arr[i];
            arr[i] = arr[j];
            arr[j] = temp;
            i++;
            j--;
        }
    }
    
    if (L<j) {
        [self quickSort:arr L:L R:j];
    }
    if (i<R) {
        [self quickSort:arr L:i R:R];
    }
}