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   3Output:1

Example 2: 

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