50. Pow(x, n)

題目描述

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

範例

Example 1:

Input: x = 2.00000, n = 10
Output: 1024.00000

Example 2:

Input: x = 2.10000, n = 3
Output: 9.26100

Example 3:

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

Constraints:

• -100.0 < x < 100.0
• -2³¹ <= n <= 2³¹-1
• n is an integer.
• Either x is not zero or n > 0.
• -10⁴ <= xⁿ <= 10⁴

解答

Javascript

function myPow(x, n) {
  let result = 1;
  while (n) {
    if (n % 2) {
      if (n > 0) {
        result *= x;
      } else {
        result /= x;
      }
    }

    x = x * x;
    n = ~~(n / 2);
  }

  return result;
}

MarsgoatJul 24, 2023

C++

class Solution {
public:
    double myPow(double base, int n) {
        long long exponent = (long long) n;
        if (exponent == 0) {
            return 1;
        }
        if (exponent < 0) {
            base = 1 / base;
            exponent = -exponent;
        }
        double ans = 1;
        while (exponent > 0) {
            if (exponent % 2 == 1) {
                ans *= base;
                exponent -= 1;
            }
            base = base * base;
            exponent /= 2;
        }
        return ans;
    }

    template<typename T>
    void printVector(const vector<T>& vec) {
        for (const T& element : vec) {
            cout << element << ",";
        }
        cout << endl;
    }
};

Jerry Wu24 July, 2023

Reference

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