Pow(x, n) 

 1 public class Solution {
 2     public double pow(double x, int n) {
 3         if(x==0||x==1) return x;
 4         if(n<0)return 1/helper(x,-1*n);
 5         else return helper(x,n);
 6     }
 7     public double helper(double x,int n){
 8         if(n==0) return 1;
 9         double res = helper(x,n/2);
10         if(n%2==0) return res*res;
11         else return res*res*x;
12     }
13 }
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posted @ 2014-02-06 14:18  krunning  阅读(105)  评论(0)  编辑  收藏  举报