feat: Add solution for 1863 Sum of All Subset XOR Totals

Author: Shamik07

1123-lowest-ancestor-leaves.dart

@@ -0,0 +1,92 @@
+import 'dart:collection';
+import 'dart:math';
+
+class TreeNode {
+  int val;
+  TreeNode? left;
+  TreeNode? right;
+  TreeNode([this.val = 0, this.left, this.right]);
+
+  @override
+  String toString() {
+    return 'TreeNode{val: $val}';
+  }
+}
+
+class LcaResult {
+  int depth;
+  TreeNode? lca;
+  LcaResult(this.depth, this.lca);
+}
+
+class Solution {
+  LcaResult _dfs(TreeNode? node) {
+    if (node == null) {
+      return LcaResult(-1, null);
+    }
+
+    LcaResult leftResult = _dfs(node.left);
+    LcaResult rightResult = _dfs(node.right);
+
+    int currentDepth = max(leftResult.depth, rightResult.depth) + 1;
+
+    if (leftResult.depth > rightResult.depth) {
+      return LcaResult(currentDepth, leftResult.lca);
+    } else if (rightResult.depth > leftResult.depth) {
+      return LcaResult(currentDepth, rightResult.lca);
+    } else {
+      // equal
+      return LcaResult(currentDepth, node);
+    }
+  }
+
+  TreeNode? lcaDeepestLeaves(TreeNode? root) {
+    if (root == null) {
+      return null;
+    }
+    LcaResult result = _dfs(root);
+    return result.lca;
+  }
+}
+
+TreeNode? buildTree(List<int?> values) {
+  if (values.isEmpty || values[0] == null) {
+    return null;
+  }
+
+  TreeNode root = TreeNode(values[0]!);
+  Queue<TreeNode> queue = Queue<TreeNode>();
+  queue.add(root);
+  int i = 1;
+
+  while (queue.isNotEmpty && i < values.length) {
+    TreeNode current = queue.removeFirst();
+
+    if (i < values.length && values[i] != null) {
+      current.left = TreeNode(values[i]!);
+      queue.add(current.left!);
+    }
+    i++;
+
+    if (i < values.length && values[i] != null) {
+      current.right = TreeNode(values[i]!);
+      queue.add(current.right!);
+    }
+    i++;
+  }
+  return root;
+}
+
+void main() {
+  final solution = Solution();
+
+  List<int?> values1 = [3, 5, 1, 6, 2, 0, 8, null, null, 7, 4];
+  TreeNode? root1 = buildTree(values1);
+  TreeNode? lca1 = solution.lcaDeepestLeaves(root1);
+  print("Example 1 LCA: ${lca1?.val}"); // Expected output: 2
+
+  List<int?> values2 = [1];
+  TreeNode? root2 = buildTree(values2);
+  TreeNode? lca2 = solution.lcaDeepestLeaves(root2);
+  print("Example 2 LCA: ${lca2?.val}"); // Expected output: 1
+}

1863-sum-subset-xor.dart

@@ -0,0 +1,32 @@
+int subsetXORSum(List<int> nums) {
+  if (nums.isEmpty) {
+    return 0;
+  }
+
+  int orSum = 0;
+  for (int num in nums) {
+    orSum |= num;
+  }
+
+  // bit shift
+  int multiplier = 1 << (nums.length - 1);
+
+  return orSum * multiplier;
+}
+
+void main() {
+  // Example 1
+  List<int> nums1 = [1, 3];
+  int result1 = subsetXORSum(nums1);
+  print("Input: $nums1, Output: $result1"); // Expected: 6
+
+  // Example 2
+  List<int> nums2 = [5, 1, 6];
+  int result2 = subsetXORSum(nums2);
+  print("Input: $nums2, Output: $result2"); // Expected: 28
+
+  // Example 3
+  List<int> nums3 = [3, 4, 5, 6, 7, 8];
+  int result3 = subsetXORSum(nums3);
+  print("Input: $nums3, Output: $result3"); // Expected: 480
+}