Codeforces Round #257 (Div. 2) B. Jzzhu and Sequences

B. Jzzhu and Sequences

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

題目意思很簡單  給出三個數x，y，n，其中x=f1,y=f2    fi+1=fi-fi-1;

求出fn%(10^9+7)

一個周期函數。。。。。水過

#include<iostream>
#define M  1000000007
#define N 2000000000+5
using namespace std;
int main()
{
    __int64 ans,n,x,y,i;
    int a[7];
    while(cin>>x>>y)
    {
        cin>>n;
        n=n%6;
            x=(x+M)%M;
            y=(y+M)%M;
            a[1]=x;
            a[2]=y;
        for(i=2;i<7;i++)
        {
            if(a[i<0])
                a[i]=(a[i]+M)%M;
            else if(i>2)
                a[i]=a[i]%M;
            a[i+1]=(a[i]-a[i-1])%M;
        }
        if(n)
        cout<<a[n]<<endl;
        else cout<<a[6]<<endl;


    }
}