标签：des style blog java color for
Given a binary tree, return the level order traversal of its nodes‘ values. (ie, from left to right, level by level).
For example:
Given binary tree {3,9,20,#,#,15,7},
3
/ 9 20
/ 15 7
return its level order traversal as:
[ [3], [9,20], [15,7] ]
实现的关键在于定义两个标记位和队列：
1、标志位last和end。last为记录的是本层次的最后一个最后一个结点，end用于寻找下一层的最后一个结点。
2、队列是用于存储每个结点。
public class Solution { public List<List<Integer>> levelOrder(TreeNode root) { List<List<Integer>> list = new ArrayList<>(); List<Integer> lst = new ArrayList<>(); Queue<TreeNode> queue = new LinkedList<>(); queue.add(root); TreeNode last =root; TreeNode end = null; while(!queue.isEmpty()){ TreeNode t = queue.remove(); if(t!=null){ lst.add(t.val); if(t.left != null){ queue.add(t.left); end = t.left; } if(t.right != null){ queue.add(t.right); end = t.right; } if(t == last ){ list.add(lst); last =end; lst = new ArrayList<>(); } } } return list; } }
Binary Tree Level Order Traversal java实现,布布扣,bubuko.com
Binary Tree Level Order Traversal java实现
标签：des style blog java color for
原文地址：http://www.cnblogs.com/rolly-yan/p/3832636.html
