数值处理 - Sqrt(x)

一，Sqrt(x)

题目描述

Implement int sqrt(int x).

Compute and return the square root of x.

我的代码

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) / 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;  
        } 
    }
};