hdu 1005

Number Sequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 68201    Accepted Submission(s): 15821

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 31 2 100 0 0

 

Sample Output

25

 

Author

CHEN, Shunbao

 

Source

ZJCPC2004

 

Recommend

JGShining

 

#include <iostream>using namespace std;int main(){    int i,n,a,b,f[100];    while (cin>>a>>b>>n)     {        f[1] = 1,f[2] = 1;        if(a == 0 && b == 0 && n == 0)            break;        if(n >= 3)        {            for (i = 3; i < 100; i++)             {                f[i] = (a*f[i-1] + b*f[i - 2]) % 7;                if(f[i] == 1 && f[i-1] == 1)                    break;            }            i = i - 2;            n = n % i;//i-2 is the cycle of ruslt            if (n == 0)             {                n = i;             }            cout<<f[n]<<endl;        }        else            cout<<"1"<<endl;            }    return 0;}