Leetcode 50. Pow(x, n)

Tyan

发布于 2019-05-25 22:53:12

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发布于 2019-05-25 22:53:12

文章被收录于专栏：SnailTyanSnailTyan

文章作者：Tyan

博客：noahsnail.com | CSDN | 简书

1. Description

2. Solution

Iterative

class Solution {
public:
    double myPow(double x, int n) {
        double result = 1.0;
        long m = labs(n);
        x = n>0?x:1/x;
        while(m) {
            if(m & 1) {
                result *= x;
            }
            x *= x;
            m >>= 1;
        }
        return result;
    }
};

Recursive

class Solution {
public:
    double myPow(double x, int n) {
        x = n>0?x:1/x;
        long m = labs(n);
        return power(x, m);
    }

    double power(double x, long n) {
        if(n == 0) {
            return 1;
        }
        if(n % 2) {
            return x * power(x * x, n / 2);
        }
        else {
            return power(x * x, n / 2);
        }
    }
};