題目描述

給定一個double型別的浮點數base和int型別的整數exponent。求base的exponent次方。

C++

/*
功能測試：base=2,exponent=32
邊界測試：base=0,exponent=-1 return
        base!=0,exponent=1,0,-1
錯誤輸入：
*/
class Solution {
public:
    bool g_InvalidInput=false;
    double Power(double base, int exponent) {
        g_InvalidInput=false;
        if(base==0&&exponent<0)
        {
            g_InvalidInput=true;
            return 0.0;
        }
        int absexponent=exponent;
        if(exponent<0)
        {
            absexponent=-exponent;
        }
        double result=PowerWithUnsignedExponent(base,absexponent);
        if(exponent<0)
        {
            result=1.0/result;
        }
        return result;
    }
    double PowerWithUnsignedExponent(double base,int exponent)
    {
        double result=1.0;
        for(int i=0;i<exponent;i++)
        {
            result*=base;
        }
        return result;
    }
};
 

Java

public class Solution {
    public double Power(double base, int exponent) {
        // 當底數為0，指數為負數時，則丟擲異常或者返回0.0
        if (equal(base, 0) && exponent < 0) {
            return 0.0;
        }
 
        // 先對指數進行取絕對值計算
        int absExponent = Math.abs(exponent);
        double result = powerWithExponent(base, absExponent);
 
        // 判斷如果傳入的指數是負數，進行取反，否則直接返回
        if (exponent < 0) {
            result = 1.0 / result;
        }
        return result;
  }
     
    // 計算數值的整數次方
    public double powerWithExponent(double base, int absExponent) {
        double result = 1.0;
        for (int i = 1; i <= absExponent; ++i) {
            result *= base;
        }
        return result;
    }
     
    // 判斷兩個double型別的數值是否相等
    public boolean equal(double num1, double num2) {
        if ((num1 - num2 > -0.0000001) && (num1 - num2 < 0.0000001)) {
            return true;
        } else
            return false;
    }
     
}
 

python

# -*- coding:utf-8 -*-
class Solution:
    def Power(self, base, exponent):
        # write code here
        result = 1.0
        if exponent >= 0:
            for i in range(exponent):
                result *= base
        else:
            for i in range(abs(exponent)):
                result *= base
            result = 1.0/result
        return result