Cod sursa(job #2726116)

Utilizator vladm98Munteanu Vlad vladm98 Data 20 martie 2021 13:01:42
Problema Al k-lea termen Fibonacci Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.15 kb
#include <bits/stdc++.h>

using namespace std;

int MOD = 666013;

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

void fastExp(int a[2][2], int k) {
    int rez[2][2] = {{1, 0}, {0, 1}};
    while (k > 0) {
        if (k % 2 == 1) {
            mulMatrix(rez, a);
            mulMatrix(a, a);
            k = (k - 1) / 2;
        } else {
            mulMatrix(a, a);
            k = k / 2;
        }
    }
    for (int i = 0; i < 2; ++i) {
        for (int j = 0; j < 2; ++j) {
            a[i][j] = rez[i][j];
        }
    }
}

int main()
{
    ifstream fin("kfib.in");
    ofstream fout("kfib.out");
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int k;
    fin >> k;
    int a[2][2] = {{0, 1}, {1, 1}};
    fastExp(a, k);
    fout << a[1][0];
    return 0;
}