|
5 | 5 | importjava.util.LinkedList; |
6 | 6 | importjava.util.Queue; |
7 | 7 |
|
8 | | -/** |
9 | | - * 226. Invert Binary Tree |
10 | | -
|
11 | | - Invert a binary tree. |
12 | | -
|
13 | | - 4 |
14 | | - / \ |
15 | | - 2 7 |
16 | | - / \ / \ |
17 | | -1 3 6 9 |
18 | | -
|
19 | | -to |
20 | | -
|
21 | | - 4 |
22 | | - / \ |
23 | | - 7 2 |
24 | | - / \ / \ |
25 | | -9 6 3 1 |
26 | | -
|
27 | | -Trivia: |
28 | | -This problem was inspired by this original tweet by Max Howell: |
29 | | -Google: 90% of our engineers use the software you wrote (Homebrew), |
30 | | - but you can�t invert a binary tree on a whiteboard so fuck off. |
31 | | - */ |
32 | 8 | publicclass_226 { |
33 | 9 |
|
34 | | -publicstaticclassSolution1 { |
35 | | -publicTreeNodeinvertTree(TreeNoderoot) { |
36 | | -if (root ==null) { |
37 | | -returnroot; |
38 | | -} |
39 | | -Queue<TreeNode>q =newLinkedList(); |
40 | | -q.offer(root); |
41 | | -while (!q.isEmpty()) { |
42 | | -TreeNodecurr =q.poll(); |
43 | | -TreeNodetemp =curr.left; |
44 | | -curr.left =curr.right; |
45 | | -curr.right =temp; |
46 | | -if (curr.left !=null) { |
47 | | -q.offer(curr.left); |
48 | | -} |
49 | | -if (curr.right !=null) { |
50 | | -q.offer(curr.right); |
51 | | -} |
52 | | -} |
53 | | -returnroot; |
54 | | -} |
55 | | -} |
56 | | - |
57 | | -publicstaticclassSolution2 { |
58 | | -publicTreeNodeinvertTree(TreeNoderoot) { |
59 | | -if (root ==null) { |
60 | | -returnroot; |
61 | | -} |
62 | | -TreeNodetemp =root.left; |
63 | | -root.left =root.right; |
64 | | -root.right =temp; |
65 | | -invertTree(root.left); |
66 | | -invertTree(root.right); |
67 | | -returnroot; |
68 | | -} |
69 | | -} |
70 | | - |
71 | | -publicstaticclassSolution3 { |
72 | | -//more concise version |
73 | | -publicTreeNodeinvertTree(TreeNoderoot) { |
74 | | -if (root ==null) { |
75 | | -returnroot; |
76 | | -} |
77 | | -TreeNodetemp =root.left; |
78 | | -root.left =invertTree(root.right); |
79 | | -root.right =invertTree(temp); |
80 | | -returnroot; |
81 | | -} |
82 | | -} |
| 10 | +publicstaticclassSolution1 { |
| 11 | +publicTreeNodeinvertTree(TreeNoderoot) { |
| 12 | +if (root ==null) { |
| 13 | +returnroot; |
| 14 | +} |
| 15 | +Queue<TreeNode>q =newLinkedList(); |
| 16 | +q.offer(root); |
| 17 | +while (!q.isEmpty()) { |
| 18 | +TreeNodecurr =q.poll(); |
| 19 | +TreeNodetemp =curr.left; |
| 20 | +curr.left =curr.right; |
| 21 | +curr.right =temp; |
| 22 | +if (curr.left !=null) { |
| 23 | +q.offer(curr.left); |
| 24 | +} |
| 25 | +if (curr.right !=null) { |
| 26 | +q.offer(curr.right); |
| 27 | +} |
| 28 | +} |
| 29 | +returnroot; |
| 30 | +} |
| 31 | +} |
| 32 | + |
| 33 | +publicstaticclassSolution2 { |
| 34 | +publicTreeNodeinvertTree(TreeNoderoot) { |
| 35 | +if (root ==null) { |
| 36 | +returnroot; |
| 37 | +} |
| 38 | +TreeNodetemp =root.left; |
| 39 | +root.left =root.right; |
| 40 | +root.right =temp; |
| 41 | +invertTree(root.left); |
| 42 | +invertTree(root.right); |
| 43 | +returnroot; |
| 44 | +} |
| 45 | +} |
| 46 | + |
| 47 | +publicstaticclassSolution3 { |
| 48 | +//more concise version |
| 49 | +publicTreeNodeinvertTree(TreeNoderoot) { |
| 50 | +if (root ==null) { |
| 51 | +returnroot; |
| 52 | +} |
| 53 | +TreeNodetemp =root.left; |
| 54 | +root.left =invertTree(root.right); |
| 55 | +root.right =invertTree(temp); |
| 56 | +returnroot; |
| 57 | +} |
| 58 | +} |
83 | 59 | } |