Pow(x, n)
Implement pow(x, n).
public class Solution { public double pow(double x, int n) { //判断x是不是0 if(Math.abs(x-0)<0.0000001) return 1; //指数为负数 if(n<0){ return 1/p(x,-((long)n)); } if(n==0) return 1; return p(x,n); } public double p(double x,long n){ if(n==0) return 1; if(n==1) return x; if(n%2==0){ double r=p(x,n/2); return r*r; } double r=p(x,(n-1)/2); return r*r*x; } }