Good Paintings Solver

#include <bits/stdc++.h>
// tiom4eg's precompiler options
// POGGERS POGGERS POGGERS POGGERS POGGERS POGGERS POGGERS
// IO settings
#define fastIO ios_base::sync_with_stdio(false); cin.tie(0)
// Quick types
#define ll long long
#define pii pair <int, int>
#define pll pair <ll, ll>
#define vi vector <int>
#define mi vector <vector <int> >
// Quick functions
#define endl "\n"
#define F first
#define S second
#define all(a) a.begin(), a.end()
#define sz(a) a.size()
#define pb push_back
#define mp make_pair
// Quick fors
#define FOR(i, a, b) for (int i = a; i < b; ++i)
#define RFOR(i, a, b) for (int i = a; i >= b; --i)
// Pragmas
#pragma GCC optimize("O3,unroll-loops") // let the chaos begin!
//#pragma GCC target("avx,avx2,bmi,bmi2,popcnt,lzcnt,tune=native")
#pragma GCC comment(linker, "/stack:200000000")
// PBDS
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ordered_set tree <int, null_type, less <int>, rb_tree_tag, tree_order_statistics_node_update>
#define ook order_of_key
#define fbo find_by_order
// POGGERS POGGERS POGGERS POGGERS POGGERS POGGERS POGGERS
using namespace std;
using namespace __gnu_pbds;
mt19937 rng(std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count());

int randint(int n) {
    return rng() % n + 1;
}
/*
 ██▓     ███▄ ▄███▓ ▄▄▄       ▒█████
▓██▒    ▓██▒▀█▀ ██▒▒████▄    ▒██▒  ██▒
▒██░    ▓██    ▓██░▒██  ▀█▄  ▒██░  ██▒
▒██░    ▒██    ▒██ ░██▄▄▄▄██ ▒██   ██░
░██████▒▒██▒   ░██▒ ▓█   ▓██▒░ ████▓▒░
░ ▒░▓  ░░ ▒░   ░  ░ ▒▒   ▓▒█░░ ▒░▒░▒░
░ ░ ▒  ░░  ░      ░  ▒   ▒▒ ░  ░ ▒ ▒░
  ░ ░   ░      ░     ░   ▒   ░ ░ ░ ▒
    ░  ░       ░         ░  ░    ░ ░
*/

mi f;
int n, m, c, cur, best;

void gen() { FOR(i, 0, n) FOR(j, 0, m) f[i][j] = randint(c); }
int calc(int x, int y) {
    int res = 0;
    FOR(i, 0, n) FOR(j, 0, m) if (i != x && j != y) if (f[i][j] == f[x][j] && f[x][j] == f[i][y] && f[i][y] == f[x][y]) res++;
    return res;
}

int main(){
    fastIO;
    cin >> n >> m >> c;
    f.assign(n, vi(m));
    FOR(iter, 0, 100) {
        gen();
        cur = 0;
        FOR(i, 0, n) FOR(j, 0, m) cur += calc(i, j);
        cur >>= 2;
        best = cur;
        FOR(att, 0, 5000) {
            int i = randint(n) - 1, j = randint(m) - 1;
            int nw = f[i][j], tmp = f[i][j];
            while (nw == f[i][j]) nw = randint(c);
            cur -= calc(i, j);
            f[i][j] = nw;
            cur += calc(i, j);
            if (cur > best) {
                cur -= calc(i, j);
                f[i][j] = tmp;
                cur += calc(i, j);
            }
            best = min(best, cur);
            if (!cur) {
                FOR(k, 0, n) {
                    FOR(l, 0, m) cout << f[k][l] << ' ';
                    cout << endl;
                }
                exit(0);
            }
        }
    }
}