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Pow(x,n)

Implement pow(x, n), which calculates x raised to the power n (xn).

Example 1:

Input: 2.00000, 10
Output: 1024.00000

Example 2:

Input: 2.10000, 3
Output: 9.26100

Example 3:

Input: 2.00000, -2
Output: 0.25000
Explanation: 2-2 = 1/22 = 1/4 = 0.25

Note:

  • 100.0 < x < 100.0
  • n is a 32-bit signed integer, within the range [−231, 231 − 1]

方法一：暴力求解

class Solution {
public:
    double myPow(double x, int n) {
        long long N = n;
        if(N < 0){
            x = 1/x;
            N = -N;
        }
        double ans = 1;
        for(int i = 0;i < N;i++){
            ans *= x; 
        }
        return ans;
    }
};

c++ solution:

  • 时间复杂度：O(n)
  • 空间复杂度：O(1)