Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit c6c04e9

Browse files
Readability improvements to SinglyLL implementation (#5 IP)
1 parent f71a3eb commit c6c04e9

File tree

1 file changed

+51
-59
lines changed

1 file changed

+51
-59
lines changed

‎Data-Structures/Linked-Lists/LinkedList.ts

Lines changed: 51 additions & 59 deletions
Original file line numberDiff line numberDiff line change
@@ -19,6 +19,16 @@ export default class LinkedList<T> {
1919
return this.length === 0;
2020
}
2121

22+
/**
23+
* Remove all nodes from list. Constant Time O(1)
24+
*/
25+
public empty(): boolean {
26+
this.head = null;
27+
this.tail = null;
28+
this.length = 0;
29+
return true;
30+
}
31+
2232
public append(value: T): boolean {
2333
const newNode = new Node(value);
2434

@@ -61,17 +71,11 @@ export default class LinkedList<T> {
6171
return true;
6272
}
6373

64-
6574
const newNode = new Node(value);
6675

67-
let currentNode: Node<T> = this.head;
68-
69-
for (let i=0; i < atIndex-1; ++i) {
70-
currentNode = currentNode.getNext();
71-
}
72-
73-
newNode.setNext(currentNode.getNext());
74-
currentNode.setNext(newNode);
76+
let currentNode = this._traverseToNode(atIndex-1);
77+
newNode.setNext(currentNode?.getNext());
78+
currentNode?.setNext(newNode);
7579

7680
++this.length;
7781

@@ -86,22 +90,14 @@ export default class LinkedList<T> {
8690

8791
if (index===0) {
8892
value = this.head.getValue();
89-
this.head = this.head.getNext();
93+
this.head = this.head.getNext();// Manipulate pointers to mark deleted Node for garbage collection
9094
}
9195
else {
92-
let currentNode = this.head;
93-
94-
for (let i=0; i < index; ++i) { // Traverse linked list to find Node index-1
95-
if (i===index-1) {
96-
value = currentNode.getNext().getValue(); // Store Node value
97-
break;
98-
}
99-
currentNode = currentNode.getNext();
100-
}
101-
currentNode.setNext(currentNode.getNext().getNext()); // Manipulate pointers to mark deleted Node for garbage collection
96+
let leader = this._traverseToNode(index-1);
97+
value = leader?.getNext().getValue();
98+
leader?.setNext(leader.getNext().getNext()); // Manipulate pointers to mark deleted Node for garbage collection
10299
}
103-
104-
--this.length; // Decrement length
100+
--this.length; // Decrement length
105101

106102
return value;
107103
}
@@ -111,14 +107,8 @@ export default class LinkedList<T> {
111107
if (this.length === 0 || !this.head || !this.tail) return null; // Verify that list is not empty
112108
if (index === this.length-1) return this.tail.getValue(); // Optimization when retrieving last element
113109

114-
let currentNode = this.head;
115-
116-
for (let i=0; i <= index; ++i) {
117-
if (i===index) return currentNode.getValue();
118-
currentNode = currentNode.getNext();
119-
}
120-
121-
return null;
110+
let targetNode = this._traverseToNode(index);
111+
return targetNode?.getValue() || null;
122112
}
123113

124114
/**
@@ -139,22 +129,24 @@ export default class LinkedList<T> {
139129
return null;
140130
}
141131

142-
/**
143-
* Remove all nodes from list. Constant Time O(1)
144-
*/
145-
public empty(): boolean {
146-
this.head = null;
147-
this.tail = null;
148-
this.length = 0;
149-
return true;
132+
private _traverseToNode(index: number): Node<T> | null {
133+
if (!this.head) return null;
134+
135+
let currentNode = this.head;
136+
137+
for (let i=0; i<index; ++i) {
138+
currentNode = currentNode.getNext();
139+
}
140+
141+
return currentNode;
150142
}
151143

152144
public toString(nodesPerGroup?: number): string {
153145
if (this.length === 0 || !this.head) {
154146
return "";
155147
}
156148

157-
nodesPerGroup = nodesPerGroup ? nodesPerGroup : 8;
149+
nodesPerGroup = nodesPerGroup ? nodesPerGroup : 6;
158150

159151
const LABEL_HEAD = 'HEAD';
160152
const LABEL_TAIL = 'TAIL';
@@ -163,7 +155,7 @@ export default class LinkedList<T> {
163155
let currentNode: Node<any> = this.head;
164156

165157
for (let i=0; i < this.length; ++i) {
166-
listAsString += `${Array(i%nodesPerGroup).fill('\t').join('')} ${i===0 ? LABEL_HEAD : '–'} ${currentNode} ${i===this.length-1 ? LABEL_TAIL : ''}\n`;
158+
listAsString += `${Array(i%nodesPerGroup).fill('\t').join('')} ${i===0 ? LABEL_HEAD : i} ${currentNode} ${i===this.length-1 ? LABEL_TAIL : ''}\n`;
167159

168160
if (currentNode.hasNext()) {
169161
currentNode = currentNode.getNext();
@@ -249,16 +241,16 @@ if (import.meta.main) {
249241
// --------------------------- Terminal Output: ---------------------------
250242
// --- Node Count: 3
251243
// HEAD { value: "Appa", next: true }
252-
// – { value: "Sokka", next: true }
253-
// – { value: "Katara", next: false } TAIL
254-
//
244+
// 1 { value: "Sokka", next: true }
245+
// 2 { value: "Katara", next: false } TAIL
246+
255247
// --- Node Count: 6
256248
// HEAD { value: "Appa", next: true }
257-
// – { value: "Zuko", next: true }
258-
// – { value: "Sokka", next: true }
259-
// – { value: "Aang", next: true }
260-
// – { value: "Iroh", next: true }
261-
// – { value: "Katara", next: false } TAIL
249+
// 1 { value: "Zuko", next: true }
250+
// 2 { value: "Sokka", next: true }
251+
// 3 { value: "Aang", next: true }
252+
// 4 { value: "Iroh", next: true }
253+
// 5 { value: "Katara", next: false } TAIL
262254
//
263255
// "Iroh" found at index: 4
264256
// "Sok" found at index: null
@@ -271,28 +263,28 @@ if (import.meta.main) {
271263
// Removing element at index 1: "Zuko"
272264
// --- Node Count: 5
273265
// HEAD { value: "Appa", next: true }
274-
// – { value: "Sokka", next: true }
275-
// – { value: "Aang", next: true }
276-
// – { value: "Iroh", next: true }
277-
// – { value: "Katara", next: false } TAIL
266+
// 1 { value: "Sokka", next: true }
267+
// 2 { value: "Aang", next: true }
268+
// 3 { value: "Iroh", next: true }
269+
// 4 { value: "Katara", next: false } TAIL
278270
//
279271
// Removing element at index 0: "Appa"
280272
// --- Node Count: 4
281273
// HEAD { value: "Sokka", next: true }
282-
// – { value: "Aang", next: true }
283-
// – { value: "Iroh", next: true }
284-
// – { value: "Katara", next: false } TAIL
274+
// 1 { value: "Aang", next: true }
275+
// 2 { value: "Iroh", next: true }
276+
// 3 { value: "Katara", next: false } TAIL
285277
//
286278
// Removing element at index 2: "Iroh"
287279
// --- Node Count: 3
288280
// HEAD { value: "Sokka", next: true }
289-
// – { value: "Aang", next: true }
290-
// – { value: "Katara", next: false } TAIL
281+
// 1 { value: "Aang", next: true }
282+
// 2 { value: "Katara", next: false } TAIL
291283
//
292284
// Removing element at index 2: "Katara"
293285
// --- Node Count: 2
294286
// HEAD { value: "Sokka", next: true }
295-
// – { value: "Aang", next: false } TAIL
287+
// 1 { value: "Aang", next: false } TAIL
296288
//
297289
// Removing element at index 1: "Aang"
298290
// Removing element at index 0: "Sokka"
@@ -303,4 +295,4 @@ if (import.meta.main) {
303295
//
304296
// --- Node Count: 2
305297
// HEAD { value: "Katara", next: true }
306-
// – { value: "Aang", next: false } TAIL
298+
// 1 { value: "Aang", next: false } TAIL

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /