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
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
public class {
public static void preOrder0(TreeNode root, ArrayList<Integer> result) {
if (root != null) {
result.add(root.val);
preOrder0(root.left, result);
preOrder0(root.right, result);
}
}
public static void inOrder0(TreeNode root, ArrayList<Integer> result) {
if (root != null) {
inOrder0(root.left, result);
result.add(root.val);
inOrder0(root.right, result);
}
}
public static void postOrder0(TreeNode root, ArrayList<Integer> result) {
if (root != null) {
postOrder0(root.left, result);
postOrder0(root.right, result);
result.add(root.val);
}
}
public static void preOrder(TreeNode root, ArrayList<Integer> result) {
if(root == null)return;
Stack<TreeNode> stack = new Stack<>();
stack.push(root);
while (!stack.empty()) {
TreeNode node = stack.pop();
result.add(node.val);
if (node.right != null) stack.push(node.right);
if (node.left != null) stack.push(node.left);
}
}
public static void inOrder(TreeNode root, ArrayList<Integer> result) {
if(root == null)return;
Stack<TreeNode> stack = new Stack<>();
while (!stack.empty() || root != null) {
while (root != null) {
stack.push(root);
root = root.left;
}
root = stack.pop();
result.add(root.val);
root = root.right;
}
}
public static void postOrder(TreeNode root, ArrayList<Integer> result){
if(root == null)return;
Stack<TreeNode> first = new Stack<>();
Stack<TreeNode> last = new Stack<>();
first.push(root);
while(!first.empty()){
TreeNode cur = first.pop();
last.push(cur);
if(cur.left != null)first.push(cur.left);
if(cur.right != null)first.push(cur.right);
}
while(!last.empty()){
result.add(last.pop().val);
}
}
public static void levelOrder(TreeNode root, ArrayList<Integer> result){
if(root == null)return;
LinkedList<TreeNode> queue = new LinkedList<>();
queue.add(root);
while(!queue.isEmpty()){
TreeNode cur = queue.poll();
result.add(cur.val);
if(cur.left!=null) queue.add(cur.left);
if(cur.right!=null) queue.add(cur.right);
}
}
public static void morrisPre(TreeNode root, ArrayList<Integer> result) {
if (root == null) return;
TreeNode cur = root;
TreeNode mostRight;
while (cur != null) {
mostRight = cur.left;
if (mostRight != null) {
while (mostRight.right != null && mostRight.right != cur) {
mostRight = mostRight.right;
}
if (mostRight.right == cur) {
mostRight.right = null;
} else {
result.add(cur.val);
mostRight.right = cur;
cur = cur.left;
continue;
}
}else{
result.add(cur.val);
}
cur = cur.right;
}
}
}
|
近期评论