leetcode- Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

class Solution {
public:
    int mySqrt(int x) {
        if(x<=0) return 0;
        int begin=1, end=x, mid=0, res=0, tmp=0;
        while(begin<=end)
        {
            mid=begin+(end-begin)/2;
            tmp=x/mid;
            if(tmp>mid)
            {
                res=mid;
                begin = mid;
            }
            else if(tmp<mid)
            {
                end = end-1;
            }
            else if(tmp==mid)
            {
                res=mid;
                break;
            }
        }
        return res;
    }
};