Ruudukko

#include <bits/stdc++.h>

bool ok = false;

void solve(std::vector<int>& res, std::vector<bool>& used, int idx, int n, int m) {
    if (idx == n * m) {
        ok = true;
        std::cout << "YES\n";
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < m; ++j) {
                std::cout << res[i * m + j] << ' ';
            }
            std::cout << '\n';
        }
        return;
    }
    for (int i = n * m; !ok && i > 0; --i) {
        if (!used[i]) {
            if (idx > 0 && std::abs(res[idx - 1] - i) == 1) {
                continue;
            }
            if (idx >= m && std::abs(res[idx - m] - i) == 1) {
                continue;
            }
            used[i] = true;
            res[idx] = i;
            solve(res, used, idx + 1, n, m);
            used[i] = false;
        }
    }
}

int main() {
    int t, n, m;
    std::cin >> t;
    for (int i = 0; i < t; ++i) {
        std::cin >> n >> m;
        std::vector<int> res(n * m, n * n * m);
        ok = false;
        std::vector<bool> used(n * m + 1);
        solve(res, used, 0, n, m);
        if (!ok) {
            std::cout << "NO\n";
        }
    }
}

Test 1

Verdict: ACCEPTED