1+ 'use strict' ;
2+ class Node {
3+ constructor ( data ) {
4+ this . data = data ;
5+ this . leftNode = this . rightNode = null ;
6+ }
7+ }
8+ 9+ function leftBoundary ( root , leftBoundaryNodes ) {
10+ if ( root == null ) return ;
11+ if ( root . leftNode ) {
12+ leftBoundaryNodes . push ( root . data ) ;
13+ leftBoundary ( root . leftNode , leftBoundaryNodes ) ;
14+ } else if ( root . rightNode ) {
15+ leftBoundaryNodes . push ( root . data ) ;
16+ leftBoundary ( root . rightNode , leftBoundaryNodes ) ;
17+ }
18+ }
19+ 20+ function rightBoundary ( root , rightBoundaryNodes ) {
21+ if ( root == null ) return ;
22+ if ( root . rightNode ) {
23+ rightBoundary ( root . rightNode , rightBoundaryNodes ) ;
24+ rightBoundaryNodes . push ( root . data ) ;
25+ } else if ( root . leftNode ) {
26+ rightBoundary ( root . leftNode , rightBoundaryNodes ) ;
27+ rightBoundaryNodes . push ( root . data ) ;
28+ }
29+ }
30+ 31+ function leafNodes ( root , leafNodesArr ) {
32+ if ( root == null ) return null ;
33+ leafNodes ( root . leftNode , leafNodesArr ) ;
34+ if ( root . leftNode == null && root . rightNode == null ) {
35+ leafNodesArr . push ( root . data ) ;
36+ }
37+ leafNodes ( root . rightNode , leafNodesArr ) ;
38+ }
39+ 40+ function boundaryTraversal ( root ) {
41+ let leftBoundaryArr = [ ] ;
42+ let rightBoundaryArr = [ ] ;
43+ let leafNodesArr = [ ] ;
44+ leftBoundary ( root . leftNode , leftBoundaryArr )
45+ leafNodes ( root . leftNode , leafNodesArr ) ;
46+ leafNodes ( root . rightNode , leafNodesArr ) ;
47+ rightBoundary ( root . rightNode , rightBoundaryArr ) ;
48+ console . log ( root . data ) ;
49+ console . log ( leftBoundaryArr . join ( ',' ) ) ;
50+ console . log ( leafNodesArr . join ( ',' ) ) ;
51+ console . log ( rightBoundaryArr . join ( ',' ) ) ;
52+ }
53+ 54+ 55+ 56+ //level - 1
57+ let tree = new Node ( 1 ) ;
58+ 59+ // level - 2
60+ tree . leftNode = new Node ( 2 ) ;
61+ tree . rightNode = new Node ( 3 ) ;
62+ 63+ // level - 3
64+ tree . leftNode . leftNode = new Node ( 4 ) ;
65+ tree . leftNode . rightNode = new Node ( 5 ) ;
66+ 67+ tree . rightNode . leftNode = new Node ( 6 ) ;
68+ tree . rightNode . rightNode = new Node ( 7 ) ;
69+ 70+ // level - 4
71+ tree . leftNode . leftNode . leftNode = new Node ( 8 ) ;
72+ tree . leftNode . leftNode . rightNode = new Node ( 9 ) ;
73+ 74+ tree . leftNode . rightNode . leftNode = new Node ( 10 ) ;
75+ tree . leftNode . rightNode . rightNode = new Node ( 11 ) ;
76+ 77+ tree . rightNode . leftNode . leftNode = new Node ( 12 ) ;
78+ tree . rightNode . leftNode . rightNode = new Node ( 13 ) ;
79+ 80+ tree . rightNode . rightNode . leftNode = new Node ( 14 ) ;
81+ tree . rightNode . rightNode . rightNode = new Node ( 15 ) ;
82+ // 1
83+ // / \
84+ // 2 3
85+ // / \ / \
86+ // 4 5 6 7
87+ // / \ / \ / \ / \
88+ // 8 9 10 11 12 13 14 15
89+ boundaryTraversal ( tree ) ;
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