A1317 粉刷矩形

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

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m, k;
    cin >> n >> m >> k;

    // 用 '.' 表示还没有被粉刷的格子
    vector<string> board(n, string(m, '.'));

    for (int i = 0; i < k; i++) {
        int r, c;
        char color, dir;
        cin >> r >> c >> color >> dir;
        --r;
        --c;
        // 每次粉刷都是一条从起点一直延伸到边界的直线，后刷的覆盖先刷的
        if (dir == 'R') {
            for (int j = c; j < m; j++) board[r][j] = color;
        } else if (dir == 'L') {
            for (int j = c; j >= 0; j--) board[r][j] = color;
        } else if (dir == 'D') {
            for (int j = r; j < n; j++) board[j][c] = color;
        } else { // 'U'
            for (int j = r; j >= 0; j--) board[j][c] = color;
        }
    }

    for (const string &row : board) cout << row << "\n";
    return 0;
}