NC32 求平方根(c++)

class Solution {
public:
    
    int sqrt(int x) {
        // write code here
        if(x <= 1){
            return x;
        }
        int left = 1; 
        int right = x;//左右边界
        while(left <= right){
            int mid = (right + left) / 2;//中间值
            if(mid <= x/mid && (mid+1) > x/(mid+1)){
                return mid;// mid*mid可能溢出，所以用除法
            }else if(mid < x/mid){
                left = mid + 1;
            }else{
                right = mid - 1;
            }
        }
        return 0;
    }
};