itec 2021 pb3

#include <bits/stdc++.h>
using namespace std;
const int NDIRS = 4;
const int dirI[NDIRS] = {0, 0, -1, 1};
const int dirJ[NDIRS] = {1, -1, 0, 0};

void lee(vector<vector<int>> &mat, int si, int sj) {

    auto isIn = [=](size_t i, size_t j)->bool {
        return i >= 0 && i < mat.size() && j >= 0 && j < mat[0].size();
    };

    queue<pair<int, int>> q;
    q.push(make_pair(si, sj));
    while (!q.empty()) {
        int i = q.front().first, j = q.front().second;
        q.pop();

        for (int dir = 0; dir < NDIRS; dir++) {
            int newI = i + dirI[dir];
            int newJ = j + dirJ[dir];

            if (!isIn(newI, newJ)) {
                continue;
            }
            if (mat[newI][newJ] > mat[i][j] + 1) {
                mat[newI][newJ] = mat[i][j] + 1;
                q.push(make_pair(newI, newJ));
            }
        }
    }
}

int solve(vector<vector<int>> mat, int k) {
    const int n = mat.size(), m = mat[0].size();
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (mat[i][j] == 1) {
                mat[i][j] = 0;
            } else {
                mat[i][j] = 1e9;
            }
        }
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (mat[i][j] == 0) {
                lee(mat, i, j);
            }
        }
    }
    //for (auto it : mat) { for (int it2 : it) cerr << it2 << ' '; cerr << endl; }
    int ans = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (mat[i][j] > k) {
                ans++;
            }
        }
    }
    return ans;
}

int main() {
    vector<vector<int>> a(8, vector<int>(8));
    a[6][6] = a[2][2] = 1;
    cerr << solve(a, 2) << endl;
    return 0;
}