Cod sursa(job #2174466)

Utilizator CraiuAndrei Craiu Craiu Data 16 martie 2018 12:11:39
Problema Al k-lea termen Fibonacci Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.19 kb
#include <bits/stdc++.h>

using namespace std;

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

const int MOD = 666013;
int n;
int a[3][3], b[3][3];

inline void Copy(int a[][3], int b[][3])
{
    for(int i = 1; i <= 2; i++)
        for(int j = 1; j <= 2; j++)
            a[i][j] = b[i][j];
}

inline void Mult_Mat(int a[][3], int b[][3])
{
    int c[3][3];
    for(int i = 0; i <= 2; i++)
        for(int j = 0; j <= 2; j++)
            c[i][j] = 0;
    for(int i = 1; i <= 2; i++)
        for(int k = 1; k <= 2; k++)
            for(int j = 1; j <= 2; j++)
                c[i][j] = (c[i][j] + 1LL * a[i][k] * b[k][j]) % MOD;
    Copy(a, c);
}

inline void LgPow(int a[][3], int p)
{
    int c[3][3];
    for(int i = 0; i <= 2; i++)
        for(int j = 0; j <= 2; j++)
            c[i][j] = 0;
    c[1][1] = c[2][2] = 1;
    while(p)
    {
        if(p % 2)
            Mult_Mat(c, a);
        p /= 2;
        Mult_Mat(a, a);
    }
    Copy(a, c);
}

inline void Solve()
{
    fin >> n;
    a[1][2] = 1;
    b[1][2] = b[2][1] = b[2][2] = 1;
    LgPow(b, n - 1);
    Mult_Mat(a, b);
    fout << a[1][2];
}

int main()
{
    Solve();
    return 0;
}