数据结构与算法分析1.8

问题描述：2^100(mod 5)是多少？

代码如下：

//1.8 2^100 (mod 5)
#include <iostream>
using namespace std;

int pow(int m,int n,int d)//m^n mod d
{
    int index = 1;
    int base = m%d;//when index = 1
    while(index*2<=n){
        index = index*2;
        base = base*base%d;
    }
    while(++index<=n){
        base=base*m%d;
    }
    return base;
}
int main(){
    cout<<"2^4 mod 5:"<<pow(2,4,5)<<endl;
    cout<<"3^4 mod 6:"<<pow(3,4,6)<<endl;
    cout<<"2^5 mod 5:"<<pow(2,5,5)<<endl;
    cout<<"2^6 mod 5:"<<pow(2,6,5)<<endl;
    cout<<"2^7 mod 5:"<<pow(2,7,5)<<endl;
    cout<<"2^100 mod 5:"<<pow(2,100,5)<<endl;
    system("pause");
}