Leetcode 865 Smallest Subtree with all the Deepest Nodes

Author: jiajionline

0865_Smallest Subtree with all the Deepest Nodes/SmallestSubtreewithalltheDeepestNodes_2.java

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+class Solution {
+ private List<TreeNode> list = new ArrayList<>();
+ private int deepestLevel = 0;
+
+ public TreeNode subtreeWithAllDeepest(TreeNode root) {
+ if(root == null) return null;
+ getDeepestNodes(root,1);
+ return lowerestCommenAncestor(root, list);
+ }
+
+ private void getDeepestNodes(TreeNode node, int level) {
+ if(node == null) return;
+ if(level >= deepestLevel) {
+ if(level > deepestLevel){
+ list.clear();
+ deepestLevel = level;
+ }
+ list.add(node);
+ }
+ getDeepestNodes(node.left, level+1);
+ getDeepestNodes(node.right, level+1);
+
+ }
+
+ private TreeNode lowerestCommenAncestor(TreeNode node, List<TreeNode> list) {
+ if(node == null) return null;
+ for(TreeNode n : list) {
+ if(node == n) return node;
+ }
+ TreeNode left = lowerestCommenAncestor(node.left, list);
+ TreeNode right = lowerestCommenAncestor(node.right, list);
+ if(left != null && right != null) {
+ return node;
+ }else if(left != null){
+ return left;
+ }else{
+ return right;
+ }
+ }
+}