Cod sursa(job #930951)

Utilizator Stefex09Stefan Teodorescu Stefex09 Data 27 martie 2013 21:51:57
Problema Al k-lea termen Fibonacci Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.13 kb
#include <iostream>
#include <fstream>

using namespace std;

ifstream in ("kfib.in");
ofstream out ("kfib.out");

const int MOD = 666013;

inline void Mul (int A[3][3], int B[3][3])
{
    long long C[3][3];

    C[1][1] = (long long) 1LL * A[1][1] * B[1][1] % MOD + 1LL * A[1][2] * B[2][1];
    C[1][2] = (long long) 1LL * A[1][1] * B[1][2] % MOD + 1LL * A[1][2] * B[2][2];
    C[2][1] = (long long) 1LL * A[2][1] * B[1][1] % MOD + 1LL * A[2][2] * B[2][1];
    C[2][2] = (long long) 1LL * A[2][1] * B[1][2] % MOD + 1LL * A[2][2] * B[2][2];

    for (int i = 1; i <= 2; i ++)
        for (int j = 1; j <= 2; j ++)
            A[i][j] = C[i][j] % MOD;
}

inline int lgpow (int A[3][3], int P)
{
    int Ans[3][3];
    Ans[1][1] = 1;
    Ans[2][2] = 1;

    for ( ; P; P >>= 1){
        if (P & 1)
            Mul (Ans, A);

        Mul (A, A);
    }

    return Ans[1][2] % MOD;
}

int main()
{
    int N, A[3][3];
    A[1][1] = 0;
    A[1][2] = 1;
    A[2][1] = 1;
    A[2][2] = 1;

    in >> N;
    if (N < 3){
        out << 1;

        return 0;
    }
    out << lgpow (A, N - 3);

    return 0;
}