leetcode Sqrt(x)

class Solution {
public:
    int sqrt(int x) {
        long long left = 0;
        long long right = x/2 + 1;
        
        while(left <= right)
        {
            long long tmp = (left + right)/2 * ((left + right)/2); // 一定要注意括号，后面的括号要是少了就错了，因为会先乘再除2结果就不一样
            if (tmp == x) return (left + right)/2;
            else if (tmp > x)
                right = (left+right)/2 - 1;
            else
                left = (left+right)/2 + 1;
        }
        return right;
    }
};