13.5 沿一個方向一直走：射線與標記表

int r = sr, c = sc, steps = 0;           // 從起點出發
while (true) {
    int nr = r + dr[d], nc = c + dc[d];
    if (!inside(nr, nc) || grid[nr][nc] == '#') break;   // 出界或撞牆：停
    r = nr;  c = nc;                                       // 踏上去
    steps++;
}

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

int main() {
    int n, m, k;
    cin >> n >> m >> k;
    vector<int> r(k), c(k), s(k), t(k);   // 第 i 隻魔王的位置與移動向量
    vector<bool> alive(k, true);
    for (int i = 0; i < k; i++) cin >> r[i] >> c[i] >> s[i] >> t[i];

    vector<vector<bool>> bomb(n, vector<bool>(m, false));       // 這格有沒有炸彈
    vector<vector<bool>> exploded(n, vector<bool>(m, false));   // 這一回合被引爆的格子
    int alive_count = k;

    while (alive_count > 0) {
        // 步驟 1、2：所有活著的魔王放炸彈，然後同時移動一步
        for (int i = 0; i < k; i++) {
            if (!alive[i]) continue;
            bomb[r[i]][c[i]] = true;
            r[i] += s[i];
            c[i] += t[i];
        }

        // 步驟 3、4：出界的消失；踩到炸彈的消失，並記下要清掉的格子
        vector<pair<int, int>> cells_to_clear;
        for (int i = 0; i < k; i++) {
            if (!alive[i]) continue;
            if (r[i] < 0 || r[i] >= n || c[i] < 0 || c[i] >= m) {
                alive[i] = false;
                alive_count--;
            } else if (bomb[r[i]][c[i]]) {
                alive[i] = false;
                alive_count--;
                if (!exploded[r[i]][c[i]]) {
                    exploded[r[i]][c[i]] = true;
                    cells_to_clear.push_back({r[i], c[i]});
                }
            }
        }

        // 全部判定完才清炸彈：兩隻魔王同回合踩同一格，兩隻都要消失
        for (int i = 0; i < (int)cells_to_clear.size(); i++) {
            int x = cells_to_clear[i].first;
            int y = cells_to_clear[i].second;
            bomb[x][y] = false;
            exploded[x][y] = false;
        }
    }

    int answer = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            if (bomb[i][j]) answer++;
    cout << answer << '\n';
    return 0;
}

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

int main() {
    int n, m;
    cin >> n >> m;
    vector<vector<int>> card(n, vector<int>(m));
    vector<vector<pair<int, int>>> pos(1001);       // pos[x]：數值 x 的兩張牌各在哪
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++) {
            cin >> card[i][j];
            pos[card[i][j]].push_back({i, j});
        }

    vector<vector<bool>> removed(n, vector<bool>(m, false));   // 這格的牌拿掉了沒
    long long score = 0;
    bool changed = true;
    while (changed) {                                // 反覆做，直到一整輪都沒有牌可拿
        changed = false;
        for (int x = 0; x <= 1000; x++) {
            if (pos[x].empty()) continue;
            auto [r1, c1] = pos[x][0];
            auto [r2, c2] = pos[x][1];
            if (removed[r1][c1]) continue;           // 這一對已經拿掉了
            bool clear = false;
            if (r1 == r2) {                          // 同一列：中間的格子都要是空的
                clear = true;
                for (int c = min(c1, c2) + 1; c < max(c1, c2); c++)
                    if (!removed[r1][c]) clear = false;
            } else if (c1 == c2) {                   // 同一欄
                clear = true;
                for (int r = min(r1, r2) + 1; r < max(r1, r2); r++)
                    if (!removed[r][c1]) clear = false;
            }
            if (clear) {
                removed[r1][c1] = removed[r2][c2] = true;
                score += x;
                changed = true;
            }
        }
    }
    cout << score << '\n';
    return 0;
}