【校招面试 之 剑指offer】第16题 数值的整数次方

#include<iostream>
using namespace std;

template<typename T>
T myPow(T a, int m){
	double base = 1;
	int flag = (m < 0) ? -1 : 1;
	int n = (m < 0) ? -m : m;

	while(n > 0){
		base = base * a;
		n --;
	}
	if(flag == -1){
		if(a != 0){
			return (1/base);
		}
		cout<<"当指数为负时，0不能作为底数！"<<endl;
		exit(-1);
	}
	return base;
}
int main(){

	double a = 0;
	// int a = 2;
	int n = 10;
	cout<<"求"<<a<<"的"<<n<<"次方为："<<myPow(a, n)<<endl;
	system("pause");
	return 0;
}

#include<iostream>
using namespace std;

// 符号处理(符号处理放在递归方法中出现问题，所以拿了出来)
template<typename T>
double myPow1(T a, int m){
	int flag = (m < 0) ? -1 : 1;
	int n = (m < 0) ? -m : m;
	double result = myPow2(a, n, flag);
	cout<<result<<endl;
	if(flag == -1){
		if(a != 0){
			return (1/result);
		}
		cout<<"当指数为负时，0不能作为底数！"<<endl;
		exit(-1);
	}
	return result;
}

template<typename T>
T myPow2(T a, int n, int flag){
	double result;

	if(n == 0){
		return 0;
	}
	if(n == 1){
		return a;
	}
	if(n%2 == 0){
		result = myPow2(a, n/2, flag) * myPow2(a, n/2, flag);
	}else{
		result = myPow2(a, (n-1)/2, flag) * myPow2(a, (n-1)/2, flag) * myPow2(a, 1, flag);
	}
	return result;
}

int main(){

	double a = 0;
	// int a = 2;
	// int n = 8;
	int n = -10;
	cout<<"求"<<a<<"的"<<n<<"次方为："<<myPow1(a, n)<<endl;
	system("pause");
	return 0;
}