-
Notifications
You must be signed in to change notification settings - Fork 229
/
L31_timeToBurnATreeJava
65 lines (62 loc) · 2.38 KB
/
L31_timeToBurnATreeJava
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
import java.util.HashMap;
import java.util.*;
public class Solution
{
private static BinaryTreeNode<Integer> bfsToMapParents(BinaryTreeNode<Integer> root,
HashMap<BinaryTreeNode<Integer>, BinaryTreeNode<Integer>> mpp, int start) {
Queue<BinaryTreeNode<Integer>> q = new LinkedList<>();
q.offer(root);
BinaryTreeNode<Integer> res = new BinaryTreeNode<>(-1);
while(!q.isEmpty()) {
BinaryTreeNode<Integer> node = q.poll();
if(node.data == start) res = node;
if(node.left != null) {
mpp.put(node.left, node);
q.offer(node.left);
}
if(node.right != null) {
mpp.put(node.right, node);
q.offer(node.right);
}
}
return res;
}
private static int findMaxDistance(HashMap<BinaryTreeNode<Integer>, BinaryTreeNode<Integer>> mpp, BinaryTreeNode<Integer> target) {
Queue<BinaryTreeNode<Integer>> q = new LinkedList<>();
q.offer(target);
HashMap<BinaryTreeNode<Integer>,Integer> vis = new HashMap<>();
vis.put(target, 1);
int maxi = 0;
while(!q.isEmpty()) {
int sz = q.size();
int fl = 0;
for(int i = 0;i<sz;i++) {
BinaryTreeNode<Integer> node = q.poll();
if(node.left != null && vis.get(node.left) == null) {
fl = 1;
vis.put(node.left, 1);
q.offer(node.left);
}
if(node.right != null && vis.get(node.right) == null) {
fl = 1;
vis.put(node.right, 1);
q.offer(node.right);
}
if(mpp.get(node) != null && vis.get(mpp.get(node)) == null) {
fl = 1;
vis.put(mpp.get(node), 1);
q.offer(mpp.get(node));
}
}
if(fl == 1) maxi++;
}
return maxi;
}
public static int timeToBurnTree(BinaryTreeNode<Integer> root, int start)
{
HashMap<BinaryTreeNode<Integer>, BinaryTreeNode<Integer>> mpp = new HashMap<>();
BinaryTreeNode<Integer> target = bfsToMapParents(root, mpp, start);
int maxi = findMaxDistance(mpp, target);
return maxi;
}
}