[leetcode.com]算法题目 - Pow(x, n)

Implement pow(x, n).

class Solution {
public:
    double pow(double x, int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (0==n) return 1.0;
        if (1==n) return x;
        
        int k = abs(n);
        int remainder = k % 2;
        
        double result = 1;
        
        result = pow(x, k/2);
        result = result*result*(1==remainder?x:1);
        
        if (n>0)
            return result;
        else
            return 1.0/result; 
    }
};

思路：使用递归，思路会比较清晰。注意讨论n小于0的情况。