Leetcode 513 Find Bottom Left Tree Value

Given a binary tree, find the leftmost value in the last row of the tree.

Example 1:

Input: 2 / \ 1 3 Output: 1

Example 2: 

Input: 1 / \ 2 3 / / \ 4 5 6 / 7 Output: 7

Note: You may assume the tree (i.e., the given root node) is not NULL.

要找到最后一排最左边的node，需要从right到left进行遍历

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public int findBottomLeftValue(TreeNode root) { Queue<TreeNode> queue = new LinkedList<>(); queue.add(root); while(!queue.isEmpty()){ root = queue.poll(); if(root.right != null){ queue.add(root.right); } if(root.left != null){ queue.add(root.left); } } return root.val; } }