HDU（1005）Number Sequence

Posted 2021-01-10 gcter

Number Sequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 43278    Accepted Submission(s): 9449

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

//第一版，直接暴力递归，超时
#include<iostream>
using namespace std;
long long int fac(int A, int B, int n)
{
    if (n == 1 || n == 2)
        return 1;
    else
        return (A * fac(A,B,n - 1) + B * fac(A,B,n - 2)) % 7;
}
int main()
{
    int A, B, n;
    while (cin >> A >> B >> n&&A != 0 && B != 0 && n != 0)
    {
        cout << fac(A, B, n % 48) << endl;
    }
    return 0;
}