Cod sursa(job #2176590)

Utilizator pakistanezuPopescu Alexandru Gabriel pakistanezu Data 17 martie 2018 20:15:44
Problema Al k-lea termen Fibonacci Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.43 kb
#include <iostream>
#include <cstring>
#include <fstream>

#define MOD 666013
#define KMAX 2

void multiply_matrix(int A[KMAX][KMAX], int B[KMAX][KMAX], int C[KMAX][KMAX]) {
    int tmp[KMAX][KMAX]; //see the power function
    for (int i = 0; i < KMAX; ++i) {
        for (int j = 0; j < KMAX; ++j) {
            unsigned long long int sum = 0;
            for (int k = 0; k < KMAX; ++k) {
                sum += 1LL * A[i][k] * B[k][j];
            }
            tmp[i][j] = sum % MOD;
        }
    }
    memcpy(C, tmp, sizeof(tmp));
}

// R = C ^ n
void power_matrix(int C[KMAX][KMAX], int n, int R[KMAX][KMAX]) {
    int tmp[KMAX][KMAX];
    //tmp = I kmax
    for (int i = 0; i < KMAX; ++i) {
        for (int j = 0; j < KMAX; ++j) {
            if (i == j) {
                tmp[i][j] = 1;
            } else {
                tmp[i][j] = 0;
            }
        }
    }

    while (n != 1) {
        if (n % 2 == 0) {
            multiply_matrix(C, C, C);
            n /= 2;
        } else {
            multiply_matrix(tmp, C, tmp);
            --n;
        }
    }

    multiply_matrix(C, tmp, R);
}

int main() {
    int C[KMAX][KMAX] = {{0, 1},
                         {1, 1}};
    std::ifstream f("kfib.in");
    std::ofstream g("kfib.out");
    int n;
    f >> n;
    if (n < 2) {
        g << 1;
    } else {
        power_matrix(C, n - 2, C);
        g << (1 * C[0][1] + 1 * C[1][1]) % MOD;
    }
    f.close();
    g.close();
    return 0;
}