Monikulmio

#include <iostream>
#include <vector>

struct Piste {
    int x;
    int y;
};

int main(){
    int n, m, k;
    std::cin >> n >> m >> k;

    std::vector<Piste> kärkiPisteet(k);
    for (int i = 0; i < k; i++){
        std::cin >> kärkiPisteet[i].y >> kärkiPisteet[i].x;
        kärkiPisteet[i].x--;
        kärkiPisteet[i].y--;
    }

    std::vector<std::vector<char>> ruudukko(n, std::vector<char>(m, '.'));

    for (int i = 0; i < k; i++){
        ruudukko[kärkiPisteet[i].y][kärkiPisteet[i].x] = '*';
    }

    for (int i = 0; i < k; i++){
        Piste p1 = kärkiPisteet[i];
        Piste p2 = kärkiPisteet[(i + 1) % k];

        int dy = 0;
        int dx = 0;
        if (p2.y > p1.y) {
            dy = 1;
        } else if (p2.y < p1.y) {
            dy = -1;
        }
        if (p2.x > p1.x) {
            dx = 1;
        } else if (p2.x < p1.x) {
            dx = -1;
        }

        int y = p1.y;
        int x = p1.x;
        while (y != p2.y || x != p2.x){
            if (ruudukko[y][x] != '*'){
                if (dy == 0) {
                    ruudukko[y][x] = '=';
                } else if (dx == 0) {
                    ruudukko[y][x] = '|';
                } else if (dy == dx) {
                    ruudukko[y][x] = '\\';
                } else {
                    ruudukko[y][x] = '/';
                }
            }
            y += dy;
            x += dx;
        }
    }

    for (int i = 0; i < k; i++){
        ruudukko[kärkiPisteet[i].y][kärkiPisteet[i].x] = '*';
    }

    std::vector<std::vector<char>> Ruudukko = ruudukko;

    std::vector<std::pair<int, int>> xxx;
    xxx.push_back({0, 0});

    while (!xxx.empty()){
        auto [y, x] = xxx.back();
        xxx.pop_back();

        if (y < 0 || y >= n || x < 0 || x >= m){
            continue;
        }
        if (Ruudukko[y][x] != '.'){
            continue;
        }

        Ruudukko[y][x] = 'O';
        xxx.push_back({y - 1, x});
        xxx.push_back({y + 1, x});
        xxx.push_back({y, x - 1});
        xxx.push_back({y, x + 1});
    }
    
    for (int i = 0; i < n; i++){
        for (int j = 0; j < m; j++){
            if (ruudukko[i][j] == '.' && Ruudukko[i][j] != 'O'){
                ruudukko[i][j] = '#';
            }
            std::cout << ruudukko[i][j];
        }
        std::cout << "\n";
    }

    return 0;
}

Test 1 (public)

Verdict: ACCEPTED

Test 2 (public)

Verdict: ACCEPTED

Test 3 (public)

Verdict: ACCEPTED

Test 4 (public)

Verdict: ACCEPTED

Test 5 (public)

Verdict: ACCEPTED

Test 6 (public)

Verdict: ACCEPTED

Test 7 (public)

Verdict: ACCEPTED

Test 8 (public)

Verdict: ACCEPTED

Test 9 (public)

Verdict: ACCEPTED

Test 10 (public)

Verdict: ACCEPTED