hdu1005

Number Sequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 171693    Accepted Submission(s): 42372

Problem Description

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).

 

Input

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.

 

Output

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

 

Sample Input

1 1 3 1 2 10 0 0 0

 

Sample Output

2 5

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <map>
#include <iostream>
#include <algorithm>
int w[100];
using namespace std;
int main()
{
    int a,b,n,i,flag,first,end,j;
    while(cin>>a>>b>>n&&(a||b||n))
    {
        flag=0;
        w[0]=1;
        w[1]=1;
        w[2]=1;
        for(i=3;i<=n&&!flag;i++)
        {
            w[i]=(a*w[i-1]+b*w[i-2])%7;
            for(j=2;j<=i-1;j++)
            {
                if(w[i]==w[j]&&w[i-1]==w[j-1])
                {
                    first=j-1;
                    end=i-1;
                    flag=1;
                    break;
                }
            }
        }
        if(flag)
            printf("%d
",w[first+(n-end)%(end-first)]);
        else
            printf("%d
",w[n]);
    }
    return 0;
}