LeetCode 069 Sqrt(x) 求平方根

Implement int sqrt(int x).
Compute and return the square root of x.
x is guaranteed to be a non-negative integer.
Example 1:
Input: 4
Output: 2
Example 2:
Input: 8
Output: 2
Explanation: The square root of 8 is 2.82842..., and since we want to return an integer, the decimal part will be truncated.
（1）暴力搜索

 1 class Solution {
 2 public:
 3     int mySqrt(int x) {
 4         if(x<=0)
 5             return x;
 6         int begin=1;
 7         int end=x;
 8         int mid=0;
 9         while(begin<=end)
10         {
11             mid=(begin+end)/2;
12             if(mid==x/mid)
13                 return mid;
14             else if(mid<x/mid)
15                 begin=mid+1;
16             else
17                 end=mid-1;
18         }
19         return end;
20     }
21 };

（2）牛顿迭代

 1 class Solution {
 2 public:
 3     int mySqrt(int x)
 4     {
 5         long long v=x;
 6         while(v*v>x)
 7             v=(v+x/v)>>1;
 8         return v;
 9     }
10 };

posted on 2018-03-07 23:26  lina2014  阅读(120)  评论(0)  编辑  收藏  举报

导航