Cod sursa(job #2865911)

Utilizator cdenisCovei Denis cdenis Data 9 martie 2022 11:28:56
Problema Al k-lea termen Fibonacci Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1 kb
#include <iostream>
#include <fstream>
#include <cstring>

using namespace std;

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

const int MOD=666013;
int n;
int mat[3][3];
int rez[3][3];

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

void fibonacci(int p, int rez[][3])
{
    int c[3][3],aux[3][3];
    memcpy(c,mat,sizeof(mat));
    rez[0][0]=rez[1][1]=1;
    while(p)
    {
        if(p&1)
        {
            memset(aux,0,sizeof(aux));
            inmulteste(aux,rez,c); // rez=rez*mat;
            memcpy(rez,aux,sizeof(c));
        }
        memset(aux,0,sizeof(aux));
        inmulteste(aux,c,c); // mat=mat*mat;
        memcpy(c,aux,sizeof(aux));
        p>>=1;
    }
}

int main()
{
    fin >> n;
    mat[0][1]=mat[1][0]=mat[1][1]=1;
    fibonacci(n-1,rez);
    fout << rez[1][1];
    return 0;
}