Add 1676_Lowest_Common_Ancestor_of_a_Binary_Tree_IV.java

Author: seanprashad

Tree Depth First Search/1676_Lowest_Common_Ancestor_of_a_Binary_Tree_IV.java

@@ -0,0 +1,33 @@
+class Solution {
+    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode[] nodes) {
+        Set<TreeNode> s = new HashSet<>();
+
+        for (TreeNode n : nodes) {
+            s.add(n);
+        }
+
+        return helper(root, s);
+    }
+
+    private TreeNode helper(TreeNode root, Set<TreeNode> s) {
+        if (root == null) {
+            return null;
+        }
+
+        if (s.contains(root)) {
+            return root;
+        }
+
+        TreeNode left = helper(root.left, s);
+        TreeNode right = helper(root.right, s);
+
+        if (left == null) {
+            return right;
+        }
+        if (right == null) {
+            return left;
+        }
+
+        return root;
+    }
+}