Rightmost Digit
Time Limit:1000MS Memory Limit:32768KB 64bit IO Format:%I64d & %I64u
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).
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
Hint
In the first case, 3 * 3 * 3 = 27, so the rightmost digit is 7. In the second case, 4 * 4 * 4 * 4 = 256, so the rightmost digit is 6.
普通的算法会超时,数据量比较大,到1亿了
优化算法,分治思想.
例如:( 5^5)%10 = ((5^2)^2*5)%10;
这个过程中要取余 !
还有一种思想利用乘方尾数周期性的关系!
#include <stdio.h> #include <string.h> int mod(int a, int n) { long long x; long long ans; if(n==1||n==0) return n==0?1:a; x = mod(a, n/2); ans = x * x % 10; if(n%2==1) ans=ans*a%10 ; return (int)ans; } int main() { int t; int a; int dd; scanf("%d", &t); while(t--) { scanf("%d", &a ); dd = mod(a, a); printf("%d ", dd ); } return 0; }