OJ lintcode x的平方根

实现 int sqrt(int x) 函数，计算并返回 x 的平方根。
您在真实的面试中是否遇到过这个题？
Yes
样例
sqrt(3) = 1
sqrt(4) = 2
sqrt(5) = 2
sqrt(10) = 3

class Solution {
public:
    /**
     * @param x: An integer
     * @return: The sqrt of x
     */
    int sqrt(int x) {
        // write your code here

        int low=0;
        int high=x;
        while(low<=high){
            int mid=(low+high)/2;

            long long res=(long long)mid* (long long)mid;
            long long res1=(long long )(mid+1)*(long long)(mid+1);
            long long res2=(long long )(mid-1)*(long long )(mid-1);

            if(res==x){
                return mid;
            }
            if(x>res&&xres2){
                return mid-1;
            }

            if(x==res1){
                return mid+1;
            }

            if(x==res2){
                return mid-1;
            }

            if(x>res1){
                low=mid+1;
            }
            else
            {
                high=mid-1;
            }
        }

        return -1;
        
    }
};