Create: 0127-word-ladder.dart

dart/0127-word-ladder.dart

@@ -0,0 +1,48 @@
+class Solution {
+  List<int> findRedundantConnection(List<List<int>> edges) {
+    List<int> parent = [];
+    for (int i = 0; i < edges.length + 1; i++) {
+      parent.add(i);
+    }
+
+    List<int> sizes = List.filled(edges.length + 1, 1);
+
+    int find(int n) {
+      int p = parent[n];
+
+      while (p != parent[p]) {
+        parent[p] = parent[parent[p]];
+        p = parent[p];
+      }
+
+      return p;
+    }
+
+    bool union(int node1, int node2) {
+      int parentOf1 = find(node1);
+      int parentOf2 = find(node2);
+
+      if (parentOf1 == parentOf2) {
+        return false;
+      } else if (sizes[parentOf1] > sizes[parentOf2]) {
+        parent[parentOf2] = parentOf1;
+        sizes[parentOf1] += sizes[parentOf2];
+      } else {
+        parent[parentOf1] = parentOf2;
+        sizes[parentOf2] += sizes[parentOf1];
+      }
+
+      return true;
+    }
+
+    for (List<int> edge in edges) {
+      int node1 = edge[0];
+      int node2 = edge[1];
+      if (!union(node1, node2)) {
+        return [node1, node2];
+      }
+    }
+
+    return [];
+  }
+}

dart/0130-surrounded-regions.dart

@@ -0,0 +1,51 @@
+class Solution {
+  late List<List<String>> board;
+  late int rows;
+  late int columns;
+
+  bool isInBound(int row, int column) {
+    return 0 <= row && row < rows && 0 <= column && column < columns;
+  }
+
+  void dfs(int row, int column) {
+    if (!isInBound(row, column) || board[row][column] != 'O') {
+      return;
+    }
+
+    board[row][column] = 'T';
+
+    dfs(row + 1, column);
+    dfs(row, column + 1);
+    dfs(row - 1, column);
+    dfs(row, column - 1);
+  }
+
+  void solve(List<List<String>> board) {
+    this.board = board;
+    rows = board.length;
+    columns = board[0].length;
+
+    // Traverse the first and last columns
+    for (int column = 0; column < columns; column++) {
+      dfs(0, column);
+      dfs(rows - 1, column);
+    }
+
+    // Traverse the first and last rows
+    for (int row = 0; row < rows; row++) {
+      dfs(row, 0);
+      dfs(row, columns - 1);
+    }
+
+    // Replace all 'O' with 'X' and 'T' back to 'O'
+    for (int row = 0; row < rows; row++) {
+      for (int column = 0; column < columns; column++) {
+        if (board[row][column] == 'O') {
+          board[row][column] = 'X';
+        } else if (board[row][column] == 'T') {
+          board[row][column] = 'O';
+        }
+      }
+    }
+  }
+}