Leetcode刷题计划 第五天 x的平方根

 一道很简单的与二分法有关的题目，代码如下：

int mySqrt(int x){
    long long left = 0;
    long long right = x;
    long long a = 0;
    while(left <= right)
    {
        long long mid = left + (right - left)/2;
        if((long long)(mid * mid) <= x)
        {
            left = mid + 1;
            a = mid;
        }
        else
        {
            right = mid - 1;
        }
    }
    return a;
}