hdu 1097 A hard puzzle 快速冪取模

題目連接：http://acm.hdu.edu.cn/showproblem.php?pid=1097

分析：簡單題，快速冪取模， 因爲只要求輸出最後一位，因此開始就能夠直接mod10.

/*A hard puzzle

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 33036    Accepted Submission(s): 11821


Problem Description
lcy gives a hard puzzle to feng5166,lwg,JGShining and Ignatius: gave a and b,how to know the a^b.everybody objects to this BT problem,so lcy makes the problem easier than begin.
this puzzle describes that: gave a and b,how to know the a^b's the last digit number.But everybody is too lazy to slove this problem,so they remit to you who is wise.
 

Input
There are mutiple test cases. Each test cases consists of two numbers a and b(0<a,b<=2^30)
 

Output
For each test case, you should output the a^b's last digit number.
 

Sample Input
7 66
8 800
 

Sample Output
9
6
 

Author
eddy
*/
//快速冪取模
#include <cstdio>
#include <cstring>
int main()
{
    int a, b;
    while(~scanf("%d%d", &a, &b)){
        a = a % 10;
        int cnt = 1;
        while(b > 0){
            if(b % 2 == 1) cnt = cnt*a%10;
            b = b/2;
            a = a*a%10;
        }
        printf("%d\n", cnt);
    }
    return 0;
}