-
Notifications
You must be signed in to change notification settings - Fork 1
/
AllNodesDistanceKBinaryTree.java
90 lines (70 loc) · 2.25 KB
/
AllNodesDistanceKBinaryTree.java
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
package com.leetcode;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
public class AllNodesDistanceKBinaryTree {
//https://leetcode.com/problems/all-nodes-distance-k-in-binary-tree/
class Solution {
int K;
TreeNode target;
HashMap<TreeNode,TreeNode> mapParent;
HashSet<TreeNode> visited;
List<Integer> result;
public List<Integer> distanceK(TreeNode root, TreeNode target, int K) {
this.K = K;
result = new LinkedList<>();
mapParent = new HashMap<>();
visited = new HashSet<>();
//Prepare Graph parent
storeParent(root.left,root);
storeParent(root.right,root);
find(target,0);
return result;
}
public void storeParent(TreeNode node,TreeNode parent){
if(node == null) return;
mapParent.put(node,parent);
storeParent(node.left,node);
storeParent(node.right,node);
}
public void dfsDown(TreeNode node , int depth){
if(node == null)
return;
if(visited.contains(node))
return;
visited.add(node);
if(depth == this.K){
result.add(node.val);
}
dfsDown(node.left,depth+1);
dfsDown(node.right,depth+1);
}
public void find(TreeNode node, int distance){
if(distance > K)
return;
if(node == null)
return;
if(visited.contains(node))
return;
dfsDown(node,distance);
if(distance == K){
// no need to find more
// dont add as dfsDown must have already added it
return;
}
visited.add(node);//so next find do not visit this node
if(mapParent.containsKey(node)){
TreeNode parent = mapParent.get(node);
find(parent,distance+1);
}
}
}
//Definition for a binary tree node.
public class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) { val = x; }
}
}