【leetcode】Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

 

class Solution {
public:
    int mySqrt(int x) {
        unsigned long long begin=0;
        unsigned long long end=(x+1)/2;
        unsigned long long mid;
        unsigned long long tmp;

        while(begin<end)
        {
            mid=begin+(end-begin)/2;
            tmp=mid*mid;

            if(tmp==x) return mid;
            else if(tmp<x) begin=mid+1;
            else end=mid-1;
        }

        tmp=end*end;

        if(tmp>x)
            return end-1;
        else
            return end;
    }
};