二分查找法

#pragma mark -- 二分查找法
//非递归
int BinSearch1(int Array[], int low, int high, int key)
{
    int ret = -1;
    int mid = 0;
    
    ret = (Array != NULL) && (low >= 0) && (high > low);
    
    if (ret) {
        
        while (low <= high) {
            
            mid = (low + high) / 2;
            
            if (Array[mid] == key) {
                
                ret = mid;
                
                return ret;
                
            }else if (Array[mid] > key){
                
                high = mid - 1;
            }else{
                
                low = mid + 1;
            }
            
        }
    }
    
    return ret;
}


//递归
int BinSearch2(int Array[], int low, int high, int key)
{
    int ret = -1;
    int mid = 0;
    
    ret = (Array != NULL) && (low >= 0) && (high > low);

    if (low <= high) {
        mid = (low + high) / 2;
        
        if (Array[mid] == key) {
            return mid;
        }
        
        if (Array[mid] > key) {
            return BinSearch2(Array, low, mid - 1, key);
        }
        
        if (Array[mid] < key) {
            return BinSearch2(Array, mid + 1, high, key);
        }
    }
    return -1;
}