Hiitism

input/code.cpp: In function 'int main()':
input/code.cpp:79:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<info>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |         for (int i = 0; i < rc[k].size(); i ++) {
      |                         ~~^~~~~~~~~~~~~~
input/code.cpp:102:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<info>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  102 |         for (int j = 0; j < rc[1 - k].size(); j ++) {
      |                         ~~^~~~~~~~~~~~~~~~~~
input/code.cpp:127:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<info>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  127 |         for (int j = 0; j < rc[1 - k].size(); j ++) {
      |                         ~~^~~~~~~~~~~~~~~~~~

#include <bits/stdc++.h>
using namespace std;

struct info {
    int h, i, t;
    bool colored = true;
};


bool oneNonZero(info inf) {
    return (
        (inf.h != 0 && inf.i == 0 && inf.t == 0) || 
        (inf.h == 0 && inf.i != 0 && inf.t == 0) || 
        (inf.h == 0 && inf.i == 0 && inf.t != 0) 
    );
}

bool isBrushable(info inf) {
    return oneNonZero(inf) && inf.colored;
}

char getColor(info inf) {
    assert(oneNonZero(inf));
    // assumes oneNonZero
    if (inf.h != 0) return 'H';
    if (inf.i != 0) return 'I';
    if (inf.t != 0) return 'T';
    assert(false); // should never happpen
}

struct ans {
    int k;
    int i;
    char color;
};


int main()
{

    ios::sync_with_stdio(false);
    cin.tie(0);

    
    int n, m; cin >> n >> m;
    vector <string> input(n);
    for (int i = 0; i < n; i ++) {
        cin >> input[i];
    }

    
    // fill rows and cols
    vector <vector <info>> rc(2);
    rc[0].resize(n); // rows
    rc[1].resize(m); // cols

    for (int i = 0; i < n; i ++) {
        for (int j = 0; j < m; j ++) {
            if (input[i][j] == 'H') {
                rc[0][i].h ++;
                rc[1][j].h ++;
            } else if (input[i][j] == 'I') {
                rc[0][i].i ++;
                rc[1][j].i ++;
            } else if (input[i][j] == 'T') {
                rc[0][i].t ++;
                rc[1][j].t ++;
            } else if (input[i][j] == '.') {
                rc[0][i].colored = rc[1][j].colored = false;
            }
        }
    }
    

    vector <pair <int, int>> toBrush; // available for brushing

    // initial fill
    for (int k = 0; k < 2; k ++) {
        for (int i = 0; i < rc[k].size(); i ++) {
            if (isBrushable(rc[k][i])) {
                toBrush.emplace_back(k, i);
                rc[k][i].colored = false; // dont consider it anymore
            }
        }
    }

    vector <ans> answer;
    // processing
    while (!toBrush.empty()) {
        pair<int, int> cur = toBrush.back();
        int k = cur.first, i = cur.second;
        toBrush.pop_back();
        info el = rc[k][i];
        if (!oneNonZero(el)) {
            continue;  // all ?, ignore
        }

        // add it to answer
        answer.push_back(ans{k, i, getColor(el)});

        // relax others
        for (int j = 0; j < rc[1 - k].size(); j ++) {
            char c;
            if (k == 0) {
                c = input[i][j];
            } else {
                c = input[j][i];
            }

            if (c == 'H') {
                rc[1 - k][j].h --;
            } else if (c == 'I') {
                rc[1 - k][j].i --;
            } else if (c == 'T') {
                rc[1 - k][j].t --;
            }

            // now we may need to add it into the toBrush; duplicates are not added as they are marked as not colored
            if (isBrushable(rc[1 - k][j])) {
                toBrush.emplace_back(1 - k, j);
                // mark that we do not consider it anymore
                rc[1 - k][j].colored = false;
            }
        }

        // set the row or col to ? to check later
        for (int j = 0; j < rc[1 - k].size(); j ++) {
            if (k == 0) {
                input[i][j] = '?';
            } else {
                input[j][i] = '?';
            }
        }
    }

    // now check that everything is processed (. or ?)
    for (int i = 0; i < n; i ++) {
        for (int j = 0; j < m; j ++) {
            if (input[i][j] != '.' && input[i][j] != '?') {
                cout << "Impossible";
                return 0;
            }
        }
    }


    // and now print the answer
    cout << answer.size() << '\n';
    reverse(answer.begin(), answer.end());
    for (auto a : answer) {
        if (a.k == 0) {
            cout << "R ";
        } else {
            cout << "C ";
        }

        cout << a.i + 1 << ' ' << a.color << '\n';
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED