Cod sursa(job #2865967)

Utilizator cdenisCovei Denis cdenis Data 9 martie 2022 11:49:36
Problema Al k-lea termen Fibonacci Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.93 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])
{
    int aa[3][3],bb[3][3],cc[3][3];
    memset(cc,0,sizeof(cc));
    memcpy(aa,a,sizeof(aa));
    memcpy(bb,b,sizeof(bb));
    for(int i=0;i<2;i++)
        for(int j=0;j<2;j++)
            for(int k=0;k<2;k++)
                cc[i][j]=(cc[i][j]+1LL*aa[i][k]*bb[k][j])%MOD;
    memcpy(rez,cc,sizeof(cc));
}

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