Repository navigation
Expand file tree
/
Copy pathBinaryTreeZigzagLevelOrderTraversal.java
More file actions
71 lines (69 loc) · 2.19 KB
/
Copy pathBinaryTreeZigzagLevelOrderTraversal.java
File metadata and controls
71 lines (69 loc) · 2.19 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
/**
* 【工程】: LeetCode 包名: PACKAGE_NAME 类名: BinaryTreeZigzagLevelOrderTraversal
* 【作者】: liuyang
* 【时间】: 16/12/19 下午5:26
* 【题目】: Binary Tree Zigzag Level Order Traversal(二叉树的Z字型遍历)
* 【内容】: 给定一个二叉树,返回Z字型层次遍历的结果
* 【版本】: V1.0
* 【运行时间】:
* 【时间复杂度】:
* 【空间复杂度】:
* 【备注】:
* 【思路】:
*/
public class BinaryTreeZigzagLevelOrderTraversal {
public List<List<Integer>> zigzagLevelOrder(TreeNode root) {
List<List<Integer>> res = new ArrayList<>();
LinkedList<TreeNode> quene = new LinkedList<>();
List<Integer> arr = new ArrayList<>();
if (root == null) {
return res;
}
quene.add(root);
TreeNode last = root;
TreeNode nlast = null;
int flag = 1;//判断打印顺序
while (!quene.isEmpty()) {
TreeNode cur = quene.poll();
if (cur.left != null) {
quene.add(cur.left);
nlast = cur.left;
}
if (cur.right != null) {
quene.add(cur.right);
nlast = cur.right;
}
arr.add(cur.val);
if (cur.equals(last)) {
last = nlast;
if(flag==0){
res.add(reverse(arr));
}else{
res.add(arr);
}
arr = new ArrayList<>();
flag = flag ^ 1;
}
}
return res;
}
public List<Integer> reverse(List list){
List arr = new ArrayList();
for(int i=list.size()-1;i>=0;i--){
arr.add(list.get(i));
}
return arr;
}
public static void main(String[] args) {
TreeNode root = new TreeNode(3);
TreeNode n1 = new TreeNode(9);
TreeNode n2 = new TreeNode(20);
root.left = n1;
root.right = n2;
BinaryTreeZigzagLevelOrderTraversal t = new BinaryTreeZigzagLevelOrderTraversal();
System.out.println(t.zigzagLevelOrder(root));
}
}