[leetcode.com]算法题目 - Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

 class Solution {
 public:
     int sqrt(int x) {
         // Start typing your C/C++ solution below
         // DO NOT write int main() function
         if(x<=) return ;
         if(x==) return ;
         int small=;
         int large=x;
         int temp=x/;
         while(small<large){
             int a = x/temp;
             int b = x/(temp+);
             if (a==temp) return a;
             if (b==temp+) return b;
             if(temp<a && temp+>b)
                 return temp;
             else if(temp<a && temp+<b){
                 small=temp+;
                 temp = (small+large)/;
             }else {
                 large = temp;
                 temp = (small+large)/;
             }
         }
         return -;
     }
 };

我的答案

思路：需要在O(log n)时间内实现，并且注意用除法，防止两个int型的数相乘超过int的范围。