forked from algorithmzuo/algorithmbasic2020
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathCode02_MaxSubBSTHead.java
More file actions
136 lines (121 loc) · 3.22 KB
/
Code02_MaxSubBSTHead.java
File metadata and controls
136 lines (121 loc) · 3.22 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
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
package class13;
import java.util.ArrayList;
public class Code02_MaxSubBSTHead {
public static class Node {
public int value;
public Node left;
public Node right;
public Node(int data) {
this.value = data;
}
}
public static int getBSTSize(Node head) {
if (head == null) {
return 0;
}
ArrayList<Node> arr = new ArrayList<>();
in(head, arr);
for (int i = 1; i < arr.size(); i++) {
if (arr.get(i).value <= arr.get(i - 1).value) {
return 0;
}
}
return arr.size();
}
public static void in(Node head, ArrayList<Node> arr) {
if (head == null) {
return;
}
in(head.left, arr);
arr.add(head);
in(head.right, arr);
}
public static Node maxSubBSTHead1(Node head) {
if (head == null) {
return null;
}
if (getBSTSize(head) != 0) {
return head;
}
Node leftAns = maxSubBSTHead1(head.left);
Node rightAns = maxSubBSTHead1(head.right);
return getBSTSize(leftAns) >= getBSTSize(rightAns) ? leftAns : rightAns;
}
public static Node maxSubBSTHead2(Node head) {
if (head == null) {
return null;
}
return process(head).maxSubBSTHead;
}
// 每一棵子树
public static class Info {
public Node maxSubBSTHead;
public int maxSubBSTSize;
public int min;
public int max;
public Info(Node h, int size, int mi, int ma) {
maxSubBSTHead = h;
maxSubBSTSize = size;
min = mi;
max = ma;
}
}
public static Info process(Node X) {
if (X == null) {
return null;
}
Info leftInfo = process(X.left);
Info rightInfo = process(X.right);
int min = X.value;
int max = X.value;
Node maxSubBSTHead = null;
int maxSubBSTSize = 0;
if (leftInfo != null) {
min = Math.min(min, leftInfo.min);
max = Math.max(max, leftInfo.max);
maxSubBSTHead = leftInfo.maxSubBSTHead;
maxSubBSTSize = leftInfo.maxSubBSTSize;
}
if (rightInfo != null) {
min = Math.min(min, rightInfo.min);
max = Math.max(max, rightInfo.max);
if (rightInfo.maxSubBSTSize > maxSubBSTSize) {
maxSubBSTHead = rightInfo.maxSubBSTHead;
maxSubBSTSize = rightInfo.maxSubBSTSize;
}
}
if ((leftInfo == null ? true : (leftInfo.maxSubBSTHead == X.left && leftInfo.max < X.value))
&& (rightInfo == null ? true : (rightInfo.maxSubBSTHead == X.right && rightInfo.min > X.value))) {
maxSubBSTHead = X;
maxSubBSTSize = (leftInfo == null ? 0 : leftInfo.maxSubBSTSize)
+ (rightInfo == null ? 0 : rightInfo.maxSubBSTSize) + 1;
}
return new Info(maxSubBSTHead, maxSubBSTSize, min, max);
}
// for test
public static Node generateRandomBST(int maxLevel, int maxValue) {
return generate(1, maxLevel, maxValue);
}
// for test
public static Node generate(int level, int maxLevel, int maxValue) {
if (level > maxLevel || Math.random() < 0.5) {
return null;
}
Node head = new Node((int) (Math.random() * maxValue));
head.left = generate(level + 1, maxLevel, maxValue);
head.right = generate(level + 1, maxLevel, maxValue);
return head;
}
public static void main(String[] args) {
int maxLevel = 4;
int maxValue = 100;
int testTimes = 1000000;
for (int i = 0; i < testTimes; i++) {
Node head = generateRandomBST(maxLevel, maxValue);
if (maxSubBSTHead1(head) != maxSubBSTHead2(head)) {
System.out.println("Oops!");
}
}
System.out.println("finish!");
}
}