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Commit bde2d44

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committed
add removeIndex method to singly/doubly linked lists
1 parent f9e9010 commit bde2d44

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4 files changed

+60
-59
lines changed

4 files changed

+60
-59
lines changed

‎dist/datastructures/DoublyLinkedList.js‎

Lines changed: 9 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -68,25 +68,20 @@ class DoublyLinkedList extends SinglyLinkedList_1.default {
6868
};
6969
this.insert = (value, index) => {
7070
if (index === 0)
71-
return this.unshift(value);
71+
return this.unshift(value);// uses the doublylinkedlist's unshift/push/shift/pop as
7272
if (index === this.length)
73-
return this.push(value);
73+
return this.push(value);// they already cover logic for dealing with prev
7474
return super.insert(value, index, { prevEnabled: true });
7575
};
76+
this.removeIndex = (index) => {
77+
if (index === 0)
78+
return this.shift();
79+
if (index === this.length)
80+
return this.pop();
81+
return super.removeIndex(index, { prevEnabled: true });
82+
};
7683
}
7784
;
7885
}
7986
;
80-
const list = new DoublyLinkedList();
81-
list.push('Ron');
82-
list.push('Harry');
83-
list.push('Hermione');
84-
list.insert('Hagrid', 3);
85-
let node = list.head;
86-
for (let i = 0; i < list.length; i++) {
87-
console.log(node);
88-
if (node) {
89-
node = node.next;
90-
}
91-
}
9287
exports.default = DoublyLinkedList;

‎dist/datastructures/SinglyLinkedList.js‎

Lines changed: 22 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -108,15 +108,15 @@ class SinglyLinkedList {
108108
return selectedNode;
109109
}
110110
insert(value, index, options = { prevEnabled: false }) {
111+
if (index > this.length - 1 || index < 0)
112+
return null; // TODO: throw indexError ? user tried to insert at out of range index.
111113
if (index === 0)
112114
return this.unshift(value);
113115
if (index === this.length)
114116
return this.push(value);
115117
const { prevEnabled } = options;
116118
let newNode = new Node_1.default(value);
117119
const prevNode = this.get(index - 1);
118-
if (!prevNode)
119-
return null; // TODO: throw indexError ? user tried to insert at out of range index.
120120
// maybe move the out of bounds errors to top of function?
121121
const targetNode = prevNode.next;
122122
if (prevEnabled) {
@@ -128,17 +128,25 @@ class SinglyLinkedList {
128128
this._length++;
129129
return newNode;
130130
}
131+
removeIndex(index, options = { prevEnabled: false }) {
132+
if (index > this.length - 1 || index < 0)
133+
return null;
134+
if (index === 0)
135+
return this.shift();
136+
if (index === this.length - 1)
137+
return this.pop();
138+
const { prevEnabled } = options;
139+
const prevNode = this.get(index - 1);
140+
const targetNode = prevNode.next; // all three assert exists will be true
141+
const nextNode = targetNode.next; // because of first line's return null
142+
prevNode.next = nextNode;
143+
if (prevEnabled) {
144+
nextNode.prev = prevNode;
145+
targetNode.prev = null;
146+
}
147+
targetNode.next = null;
148+
this._length--;
149+
return targetNode;
150+
}
131151
}
132-
// const list = new SinglyLinkedList();
133-
// list.push('Ron');
134-
// list.push('Harry');
135-
// list.push('Hermione');
136-
// list.insert('Hagrid', 0);
137-
// let node = list.head;
138-
// for (let i = 0; i < list.length; i++) {
139-
// console.log(node);
140-
// if (node) {
141-
// node = node.next;
142-
// }
143-
// }
144152
exports.default = SinglyLinkedList;

‎src/datastructures/DoublyLinkedList.ts‎

Lines changed: 8 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -31,7 +31,7 @@ class DoublyLinkedList<T> extends SinglyLinkedList<T> {
3131
}
3232

3333
unshift = (value: T): _Node<T> => {
34-
let oldHead = this.head;
34+
let oldHead: _Node<T>|null = this.head;
3535
let node = super.unshift(value);
3636
if (oldHead) {
3737
oldHead.prev = node;
@@ -66,24 +66,16 @@ class DoublyLinkedList<T> extends SinglyLinkedList<T> {
6666
}
6767

6868
insert = (value: T, index: number) => {
69-
if (index === 0) return this.unshift(value);
70-
if (index === this.length) return this.push(value);
69+
if (index === 0) return this.unshift(value);// uses the doublylinkedlist's unshift/push/shift/pop as
70+
if (index === this.length) return this.push(value);// they already cover logic for dealing with prev
7171
return super.insert(value, index, { prevEnabled: true });
7272
};
73-
};
74-
7573

76-
const list = new DoublyLinkedList();
77-
list.push('Ron');
78-
list.push('Harry');
79-
list.push('Hermione');
80-
list.insert('Hagrid', 3);
81-
let node = list.head;
82-
for (let i = 0; i < list.length; i++) {
83-
console.log(node);
84-
if (node) {
85-
node = node.next;
74+
removeIndex = (index: number): _Node<T> | null => {
75+
if (index === 0) return this.shift();
76+
if (index === this.length) return this.pop();
77+
return super.removeIndex(index, { prevEnabled: true });
8678
}
87-
}
79+
};
8880

8981
export default DoublyLinkedList;

‎src/datastructures/SinglyLinkedList.ts‎

Lines changed: 21 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,5 @@
11
import _Node from './Node';
2+
import { listenerCount } from 'cluster';
23

34
interface SinglyLinkedList<T> {
45
head: null | _Node<T>;
@@ -116,13 +117,13 @@ class SinglyLinkedList<T> {
116117
}
117118

118119
insert(value: T, index: number, options: ListMethodOptions = { prevEnabled: false }): _Node<T> | null {
120+
if (index > this.length - 1 || index < 0) return null; // TODO: throw indexError ? user tried to insert at out of range index.
119121
if (index === 0) return this.unshift(value);
120122
if (index === this.length) return this.push(value);
121123

122124
const { prevEnabled } = options;
123125
let newNode = new _Node(value);
124-
const prevNode = this.get(index - 1);
125-
if (!prevNode) return null; // TODO: throw indexError ? user tried to insert at out of range index.
126+
const prevNode = this.get(index - 1)!;
126127
// maybe move the out of bounds errors to top of function?
127128
const targetNode = prevNode.next;
128129
if (prevEnabled) {
@@ -134,20 +135,25 @@ class SinglyLinkedList<T> {
134135
this._length++;
135136
return newNode;
136137
}
137-
}
138138

139-
// const list = new SinglyLinkedList();
140-
// list.push('Ron');
141-
// list.push('Harry');
142-
// list.push('Hermione');
143-
// list.insert('Hagrid', 0);
144-
// let node = list.head;
145-
// for (let i = 0; i < list.length; i++) {
146-
// console.log(node);
147-
// if (node) {
148-
// node = node.next;
149-
// }
150-
// }
139+
removeIndex(index: number, options: ListMethodOptions = { prevEnabled: false }): _Node<T> | null {
140+
if (index > this.length - 1 || index < 0) return null;
141+
if (index === 0) return this.shift();
142+
if (index === this.length - 1) return this.pop();
151143

144+
const { prevEnabled } = options;
145+
const prevNode = this.get(index - 1)!;
146+
const targetNode = prevNode.next!; // all three assert exists will be true
147+
const nextNode = targetNode.next!; // because of first line's return null
148+
prevNode.next = nextNode;
149+
if (prevEnabled) {
150+
nextNode.prev = prevNode;
151+
targetNode.prev = null;
152+
}
153+
targetNode.next = null;
154+
this._length--;
155+
return targetNode;
156+
}
157+
}
152158

153159
export default SinglyLinkedList;

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