hdoj 1061 Rightmost Digit【快速幂求模】

Rightmost Digit

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 39554    Accepted Submission(s):
14930

Problem Description

Given a positive integer N, you should output the most
right digit of N^N.

 

Input

The input contains several test cases. The first line
of the input is a single integer T which is the number of test cases. T test
cases follow.
Each test case contains a single positive integer
N(1<=N<=1,000,000,000).

 

Output

For each test case, you should output the rightmost
digit of N^N.

 

Sample Input

2

3

4

 

Sample Output

7

6

 

快速幂的原理其实是同余定理 （a*b）%c=（（a%c）*（a%c））%c的实现过程

#include<stdio.h>
#include<string.h>
int f(int x)
{
	int ans=1;
	int y=x;
	x=x%10;
	while(y)
	{
		if(y&1)
		    ans=(ans*x)%10;
		y/=2;
		x=(x*x)%10;
	}
	return ans;
}
int main()
{
	int n,m,j,i,t;
	scanf("%d",&t);
	while(t--)
	{
		scanf("%d",&n);
		printf("%d\n",f(n));
	}
	return 0;
}