coding-Interview/BinaryTreeLevelOrderTraversalII.java at master · arjunmullick/coding-Interview · GitHub

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package com.leetcode;

import java.util.LinkedList;

import java.util.List;

import java.util.Queue;

public class BinaryTreeLevelOrderTraversalII {

//https://leetcode.com/problems/binary-tree-level-order-traversal-ii/

class Solution {

public List<List<Integer>> levelOrderBottom(TreeNode root) {

List<List<Integer>> result = new LinkedList<>();

if(root == null) return result;

Queue<TreeNode> queue = new LinkedList<>();

queue.offer(root);

while(queue.size() > 0){

LinkedList<TreeNode> level = new LinkedList<>();

List<Integer> values = new LinkedList<>();

while(queue.size() > 0){

TreeNode node = queue.poll();

values.add(node.val);

if(node.left != null)

level.offer(node.left);

if(node.right != null)

level.offer(node.right);

}

result.add(0,values);

queue = level;

}

return result;

}

//Definition for a binary tree node.

public class TreeNode {

int val;

TreeNode left;

TreeNode right;

TreeNode() {

}

TreeNode(int val) {

this.val = val;

}

TreeNode(int val, TreeNode left, TreeNode right) {

this.val = val;

this.left = left;

this.right = right;

}

coding-Interview/BinaryTreeLevelOrderTraversalII.java at master · arjunmullick/coding-Interview · GitHub

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