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BinaryOrderLevelTraversalII.java
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BinaryOrderLevelTraversalII.java
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/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package com.alg.leetcode;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
*Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).
For example:
Given binary tree [3,9,20,null,null,15,7],
3
/ \
9 20
/ \
15 7
return its bottom-up level order traversal as:
[
[15,7],
[9,20],
[3]
]
*
*
* Solution 1:
* 1)Start from root node and for every next level, keep track of the height of the node
* 2)Store the same height elements in a list which can be stored in another list, the height being identified by the index of the outer list
* 3)Retrieve from the max height
*
* @author rbaral
*/
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class BinaryOrderLevelTraversalII {
public List<List<Integer>> levelOrderBottom(TreeNode root) {
/*
List result = new ArrayList();
result.add(Arrays.asList(new int[]{5,1,15,7}));
result.add(Arrays.asList(new int[]{9,20}));
result.add(Arrays.asList(new int[]{3}));
return result;
*/
return null;
}
}