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LeetCode-513-Find-Bottom-Left-Tree-Value.java
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LeetCode-513-Find-Bottom-Left-Tree-Value.java
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/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
// 1.BFS. Do a level order traversal.
// public int findBottomLeftValue(TreeNode root) {
// TreeNode leftMost = root;
// Queue<TreeNode> queue = new LinkedList<>();
// queue.add(root);
// while(!queue.isEmpty()) {
// // Proceed to a new level
// int size = queue.size();
// leftMost = queue.peek();
// for (int i = 0; i < size; i++) {
// TreeNode node = queue.poll();
// if (node.left != null) queue.add(node.left);
// if (node.right != null) queue.add(node.right);
// }
// }
// return leftMost.val;
// }
// 2.DFS
// https://leetcode.com/problems/find-bottom-left-tree-value/discuss/285316/Java-BFS-and-DFS
private int maxDepth = -1;
private int value;
public int findBottomLeftValue(TreeNode root) {
dfs(root, 0);
return value;
}
private void dfs(TreeNode node, int depth) {
if (node == null) return;
if (depth > maxDepth) {
value = node.val;
maxDepth = depth;
}
dfs(node.left, depth + 1);
dfs(node.right, depth + 1);
}
}