@@ -4,6 +4,7 @@ class Node {
44 this . data = data ;
55 this . previous = previous ;
66 this . next = next ;
7+ this . length = 0 ;
78 }
89}
910
@@ -21,20 +22,24 @@ class DoublyLinkedList {
2122 const newNode = new Node ( value , this . head , this . head . next ) ;
2223 this . head . next . previous = newNode ;
2324 this . head . next = newNode ;
25+ this . length += 1 ;
2426 }
2527
2628 addAtEnd ( value ) {
2729 const newNode = new Node ( value , this . tail . previous , this . tail ) ;
2830 this . tail . previous . next = newNode ;
2931 this . tail . previous = newNode ;
32+ this . length += 1 ;
3033 }
3134
3235 removeAtBeginning ( ) {
3336 this . remove ( this . head . next ) ;
37+ this . length -= 1 ;
3438 }
3539
3640 removeAtEnd ( ) {
3741 this . remove ( this . tail . previous ) ;
42+ this . length -= 1 ;
3843 }
3944
4045 remove ( node ) {
@@ -45,13 +50,7 @@ class DoublyLinkedList {
4550 }
4651
4752 length ( ) {
48- let address = this . head . next ;
49- let count = 0 ;
50- while ( address !== this . tail ) {
51- count += 1 ;
52- address = address . next ;
53- }
54- return count ;
53+ return this . length ;
5554 }
5655
5756 display ( ) {
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