1#include <vector>
2#include <queue>
3using namespace std;
4
5class Solution {
6public:
7    vector<vector<int>> findFarmland(vector<vector<int>>& land) {
8        int m = land.size();
9        int n = land[0].size();
10        vector<vector<bool>> visited(m, vector<bool>(n, false));
11        vector<vector<int>> results;
12        
13        for (int i = 0; i < m; ++i) {
14            for (int j = 0; j < n; ++j) {
15                if (land[i][j] == 1 && !visited[i][j]) {
16                    int minRow = i, minCol = j, maxRow = i, maxCol = j;
17                    queue<pair<int, int>> que;
18                    que.push({i, j});
19                    visited[i][j] = true;
20
21                    while (!que.empty()) {
22                        auto [r, c] = que.front();
23                        que.pop();
24                        maxRow = max(maxRow, r);
25                        maxCol = max(maxCol, c);
26
27                        vector<pair<int, int>> directions = {{0, 1}, {1, 0}};
28                        for (auto &[dr, dc] : directions) {
29                            int newRow = r + dr, newCol = c + dc;
30                            if (newRow < m && newCol < n && land[newRow][newCol] == 1 && !visited[newRow][newCol]) {
31                                visited[newRow][newCol] = true;
32                                que.push({newRow, newCol});
33                            }
34                        }
35                    }
36                    results.push_back({minRow, minCol, maxRow, maxCol});
37                }
38            }
39        }
40
41        return results;
42    }
43};

using System.Collections.Generic;

public class Solution {
    public int[][] FindFarmland(int[][] land) {
        int m = land.Length, n = land[0].Length;
        int[] parent = new int[m * n];
        int[] rank = new int[m * n];

        for (int i = 0; i < m * n; i++) {
            parent[i] = i;
        }

        int Find(int x) {
            if (parent[x] != x) {
                parent[x] = Find(parent[x]);
            }
            return parent[x];
        }

        void Union(int x, int y) {
            int rootX = Find(x);
            int rootY = Find(y);
            if (rootX != rootY) {
                if (rank[rootX] > rank[rootY]) {
                    parent[rootY] = rootX;
                } else if (rank[rootX] < rank[rootY]) {
                    parent[rootX] = rootY;
                } else {
                    parent[rootY] = rootX;
                    rank[rootX]++;
                }
            }
        }

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (land[i][j] == 1) {
                    int index = i * n + j;
                    if (i > 0 && land[i-1][j] == 1) {
                        Union(index, (i-1) * n + j);
                    }
                    if (j > 0 && land[i][j-1] == 1) {
                        Union(index, i * n + (j-1));
                    }
                }
            }
        }

        var bounds = new Dictionary<int, int[]>();
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (land[i][j] == 1) {
                    int root = Find(i * n + j);
                    if (!bounds.ContainsKey(root)) {
                        bounds[root] = new int[] { i, j, i, j };
                    } else {
                        bounds[root][0] = Math.Min(bounds[root][0], i);
                        bounds[root][1] = Math.Min(bounds[root][1], j);
                        bounds[root][2] = Math.Max(bounds[root][2], i);
                        bounds[root][3] = Math.Max(bounds[root][3], j);
                    }
                }
            }
        }

        var result = new List<int[]>(bounds.Values); 
        return result.ToArray();
    }
}