NYOJ427Number Sequence

Number Sequence

时间限制：1000 ms  |  内存限制：65535 KB

难度：2

 

描述

A number sequence is defined as follows:

f(1) = 1, f(2) = 1, f(n) = (A * f(n - 1) + B * f(n - 2)) mod 7.

Given A, B, and n, you are to calculate the value of f(n).

 

输入

The input consists of multiple test cases. Each test case contains 3 integers A, B and n on a single line (1 <= A, B <= 1000, 1 <= n <= 100,000,000). Three zeros signal the end of input and this test case is not to be processed.

输出

For each test case, print the value of f(n) on a single line.

样例输入

1 1 3
1 2 10
0 0 0

样例输出

2
5

 
#include<stdio.h>
int main()
{
    int f[100000];
    int a,b,n,i;
    while(scanf("%d%d%d",&a,&b,&n)&&(a||b||n))
        {
           
            f[1]=1;f[2]=1;
            if(n==1||n==2){printf("1\n");continue;}
            for(i=3;i<100000;i++)
            {
               f[i]=(a*f[i-1]+b*f[i-2])%7;
               if(f[i]==1&&f[i-1]==1) break;
            }
            i=i-2;
            f[0]=f[i];
            printf("%d\n",f[n%i]);
        }
    return 0;
}