题目描述(Medium)
Implement pow(x, n), which calculates x raised to the power n (xn).
题目链接
https://leetcode.com/problems/powx-n/description/
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 < 100.0n is a 32-bit signed integer, within the range [−231, 231 − 1]
算法分析
二分法，
提交代码：
class Solution {
public:
double myPow(double x, int n) {
if (n < 0) return power(1/x, n);
return power(x, n);
}
private:
double power(double x, int n) {
if (n == 0) return 1;
double v = power(x, n / 2);
if (n % 2 == 0) return v * v;
else
return v * v * x;
}
};
