1+ 'use strict' ;
2+ class Node {
3+ constructor ( data ) {
4+ this . data = data ;
5+ this . leftNode = this . rightNode = null ;
6+ }
7+ }
8+ 9+ function isSibling ( root , a , b ) {
10+ if ( root == null ) return true ;
11+ return ( ( root . leftNode && root . rightNode )
12+ || ( root . leftNode . data == a && root . rightNode . data == b )
13+ || ( root . rightNode . data == a && root . leftNode . data == b )
14+ || isSibling ( root . leftNode , a , b )
15+ || isSibling ( root . rightNode , a , b ) )
16+ }
17+ 18+ function findLevel ( root , data , level ) {
19+ if ( root == null ) return 0 ;
20+ if ( root . data == data ) return level ;
21+ let levelResult = findLevel ( root . leftNode , data , level + 1 ) ;
22+ if ( levelResult != 0 ) return levelResult ;
23+ return findLevel ( root . rightNode , data , level + 1 ) ;
24+ }
25+ 26+ function isCousin ( root , a , b ) {
27+ if ( root == null ) return false ;
28+ let aLevel = findLevel ( root , a , 1 ) ;
29+ let bLevel = findLevel ( root , b , 1 ) ;
30+ if ( aLevel == bLevel && ( isSibling ( root , a , b ) ) ) return true ;
31+ return false ;
32+ }
33+ 34+ //level - 1
35+ let tree = new Node ( 20 ) ;
36+ 37+ // level - 2
38+ tree . leftNode = new Node ( 8 ) ;
39+ tree . rightNode = new Node ( 6 ) ;
40+ 41+ // level -3
42+ tree . leftNode . leftNode = new Node ( 3 ) ;
43+ tree . leftNode . rightNode = new Node ( 5 ) ;
44+ 45+ tree . rightNode . leftNode = new Node ( 2 ) ;
46+ // 20
47+ // / \
48+ // 8 6
49+ // / \ /
50+ // 3 5 2
51+ let a = 3 , b = 2 ;
52+ console . log ( a + ' and ' + b + ' is cousins = ' , isCousin ( tree , a , b ) ) ;
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