hdu 1005 Number Sequence(数学题目，好好看)

1、http://acm.hdu.edu.cn/showproblem.php?pid=1005

2、题目大意：

Number Sequence

Time Limit:2000MS    Memory Limit:65536KB    64bit IO Format:%lld & %llu

SubmitStatusPracticeZOJ 2105

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

 

3、ac代码：

#include<stdio.h>int f[1000]={0,1,1};int main(){    int a,b,n;    while(scanf("%d%d%d",&a,&b,&n)!=EOF)    {        if(a==0 && b==0 && n==0)        break;//        f[0]=0;//        f[1]=1;//        f[2]=1;        int flag;        for(int i=3;i<=1000;i++)        {            f[i]= (a * f[i - 1] + b * f[i - 2])%7;            if(f[i]==f[i-1])            {                flag=i-2;                //break;            }        }        printf("%d\n",f[n%flag]);    }    return 0;}