x的平方根-LintCode

#ifndef C141_H
#define C141_H
#include<iostream>
using namespace std;
class Solution {
public:
/**
* @param x: An integer
* @return: The sqrt of x
*/
int sqrt(int x) {
// write your code here
if (x == 1)
return 1;
else if (x == 0)
return 0;
else if (x < 0)
return -1;
int left = 0, right = x;
int mid;
while (left <right)
{
mid = (left + right) >> 1;
if (x/mid==mid)
return mid;
else if (x/mid < mid)
{
right = mid-1;
}
else
{
left = mid+1;
}
}
return  x/left<left?left-1:left;
}
};
#endif