algorithm-program/50.pow-x-n.cpp at master · halu886/algorithm-program · GitHub

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/*
 * @lc app=leetcode.cn id=50 lang=cpp
 *
 * [50] Pow(x, n)
 */

// @lc code=start
class Solution
{
public:
    double fastPow(double x, long long n)
    {
        if (n == 0)
        {
            return 1.0;
        }
        double half = fastPow(x, n / 2);
        if (n % 2 == 0)
        {
            return half * half;
        }
        else
        {
            return half * half * x;
        }
    }
    double myPow(double x, int n)
    {
        long long N = n;
        if (N < 0)
        {
            x = 1 / x;
            N = -N;
        }
        return fastPow(x, N);
    }
};
// @lc code=end