Create 1568. Minimum Number of Days to Disconnect Island (#554)

Author: Chayandas07

1568. Minimum Number of Days to Disconnect Island

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+class Solution {
+public:
+    int minDays(vector<vector<int>>& grid) {
+        if (isDisconnected(grid)) return 0;
+
+        int m = grid.size();
+        int n = grid[0].size();
+
+        // Try removing one cell
+        for (int i = 0; i < m; ++i) {
+            for (int j = 0; j < n; ++j) {
+                if (grid[i][j] == 1) {
+                    grid[i][j] = 0;
+                    if (isDisconnected(grid)) return 1;
+                    grid[i][j] = 1;
+                }
+            }
+        }
+
+        // Try removing two cells
+        for (int i = 0; i < m; ++i) {
+            for (int j = 0; j < n; ++j) {
+                if (grid[i][j] == 1) {
+                    grid[i][j] = 0;
+                    for (int x = 0; x < m; ++x) {
+                        for (int y = 0; y < n; ++y) {
+                            if (grid[x][y] == 1) {
+                                grid[x][y] = 0;
+                                if (isDisconnected(grid)) return 2;
+                                grid[x][y] = 1;
+                            }
+                        }
+                    }
+                    grid[i][j] = 1;
+                }
+            }
+        }
+        return 2;
+    }
+
+private:
+    bool isDisconnected(vector<vector<int>>& grid) {
+        int m = grid.size();
+        int n = grid[0].size();
+        vector<vector<int>> visited(m, vector<int>(n, 0));
+
+        int landCount = 0;
+        for (int i = 0; i < m; ++i) {
+            for (int j = 0; j < n; ++j) {
+                if (grid[i][j] == 1) {
+                    ++landCount;
+                    if (!visited[i][j]) {
+                        if (landCount > 1) return true;
+                        bfs(grid, visited, i, j);
+                    }
+                }
+            }
+        }
+        return landCount == 0;
+    }
+
+    void bfs(vector<vector<int>>& grid, vector<vector<int>>& visited, int i, int j) {
+        int m = grid.size();
+        int n = grid[0].size();
+        queue<pair<int, int>> q;
+        q.push({i, j});
+        visited[i][j] = 1;
+
+        vector<int> dirX = {-1, 1, 0, 0};
+        vector<int> dirY = {0, 0, -1, 1};
+
+        while (!q.empty()) {
+            auto [x, y] = q.front();
+            q.pop();
+
+            for (int d = 0; d < 4; ++d) {
+                int newX = x + dirX[d];
+                int newY = y + dirY[d];
+                if (newX >= 0 && newX < m && newY >= 0 && newY < n && grid[newX][newY] == 1 && !visited[newX][newY]) {
+                    visited[newX][newY] = 1;
+                    q.push({newX, newY});
+                }
+            }
+        }
+    }
+};