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Commit f9e9010

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committed
refactor insert method
1 parent 6af1c97 commit f9e9010

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4 files changed

+97
-66
lines changed

4 files changed

+97
-66
lines changed

‎dist/datastructures/DoublyLinkedList.js‎

Lines changed: 21 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -42,16 +42,17 @@ class DoublyLinkedList extends SinglyLinkedList_1.default {
4242
};
4343
this.shift = () => {
4444
if (this.head && this.head.next) {
45-
// set new head's prev to null
4645
this.head.next.prev = null;
4746
}
4847
return super.shift();
4948
};
5049
this.get = (index) => {
5150
if (index < (this.length / 2)) {
51+
// start at head
5252
return super.get(index);
5353
}
5454
else {
55+
// count backwards from tail
5556
if (!this.tail || (index > this.length - 1 || index < 0))
5657
return null;
5758
let counter = this.length - 1;
@@ -65,9 +66,27 @@ class DoublyLinkedList extends SinglyLinkedList_1.default {
6566
return node;
6667
}
6768
};
68-
this.insert = (value, index) => super.insert(value, index, { prevEnabled: true });
69+
this.insert = (value, index) => {
70+
if (index === 0)
71+
return this.unshift(value);
72+
if (index === this.length)
73+
return this.push(value);
74+
return super.insert(value, index, { prevEnabled: true });
75+
};
6976
}
7077
;
7178
}
7279
;
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+
}
7392
exports.default = DoublyLinkedList;

‎dist/datastructures/SinglyLinkedList.js‎

Lines changed: 28 additions & 32 deletions
Original file line numberDiff line numberDiff line change
@@ -39,7 +39,8 @@ class SinglyLinkedList {
3939
}
4040
pop() {
4141
// remove last node from list
42-
// O(n) time since we have to iterate over the whole list to find the new tail, and make the new tail's next point to null.
42+
// O(n) time since we have to iterate over the whole list to find the new tail,
43+
// and make the new tail's next point to null.
4344
if (!this.head)
4445
return null;
4546
const node = this.head;
@@ -107,42 +108,37 @@ class SinglyLinkedList {
107108
return selectedNode;
108109
}
109110
insert(value, index, options = { prevEnabled: false }) {
110-
// would be nice to refactor out the prevEnabled parts to the DoublyLinkedList insert method,
111-
// but setting the prev props for surrounding nodes has to be done one way...
112-
// * this method should be cleaned up and reorganized anyways since it's too long.
111+
if (index === 0)
112+
return this.unshift(value);
113+
if (index === this.length)
114+
return this.push(value);
113115
const { prevEnabled } = options;
114116
let newNode = new Node_1.default(value);
115-
if (index === 0) {
116-
// insert as head node
117-
if (prevEnabled)
118-
newNode.prev = null;
119-
newNode.next = this.head;
120-
this.head = newNode;
121-
this._length++;
122-
return newNode;
123-
}
124-
else if (index === this.length) {
125-
// insert as tail node
126-
if (prevEnabled)
127-
newNode.prev = this.tail;
128-
this.tail.next = newNode;
129-
this.tail = newNode;
130-
}
131-
else {
132-
const prevNode = this.get(index - 1);
133-
if (!prevNode)
134-
return null; // TODO: throw indexError ? user tried to insert at out of range index.
135-
// maybe move the out of bounds errors to top of function?
136-
const targetNode = prevNode.next;
137-
if (prevEnabled) {
138-
newNode.prev = prevNode;
139-
targetNode.prev = newNode; // assert exists because ^ insert as new tail node is covered
140-
}
141-
prevNode.next = newNode;
142-
newNode.next = targetNode;
117+
const prevNode = this.get(index - 1);
118+
if (!prevNode)
119+
return null; // TODO: throw indexError ? user tried to insert at out of range index.
120+
// maybe move the out of bounds errors to top of function?
121+
const targetNode = prevNode.next;
122+
if (prevEnabled) {
123+
newNode.prev = prevNode;
124+
targetNode.prev = newNode; // assert exists because ^ insert as new tail node is covered
143125
}
126+
prevNode.next = newNode;
127+
newNode.next = targetNode;
144128
this._length++;
145129
return newNode;
146130
}
147131
}
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+
// }
148144
exports.default = SinglyLinkedList;

‎src/datastructures/DoublyLinkedList.ts‎

Lines changed: 21 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -42,16 +42,17 @@ class DoublyLinkedList<T> extends SinglyLinkedList<T> {
4242

4343
shift = (): _Node<T> | null => {
4444
if (this.head && this.head.next) {
45-
// set new head's prev to null
4645
this.head.next.prev = null;
4746
}
4847
return super.shift();
4948
}
5049
get = (index: number): _Node<T> | null => {
5150
if (index < (this.length / 2)) {
51+
// start at head
5252
return super.get(index);
5353
}
5454
else {
55+
// count backwards from tail
5556
if (!this.tail || (index > this.length - 1 || index < 0)) return null;
5657
let counter = this.length - 1;
5758
let node = this.tail;
@@ -64,8 +65,25 @@ class DoublyLinkedList<T> extends SinglyLinkedList<T> {
6465
}
6566
}
6667

67-
insert = (value: T, index: number) => super.insert(value, index, { prevEnabled: true });
68+
insert = (value: T, index: number) => {
69+
if (index === 0) return this.unshift(value);
70+
if (index === this.length) return this.push(value);
71+
return super.insert(value, index, { prevEnabled: true });
72+
};
6873
};
6974

70-
export default DoublyLinkedList;
7175

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;
86+
}
87+
}
88+
89+
export default DoublyLinkedList;

‎src/datastructures/SinglyLinkedList.ts‎

Lines changed: 27 additions & 29 deletions
Original file line numberDiff line numberDiff line change
@@ -48,7 +48,8 @@ class SinglyLinkedList<T> {
4848

4949
pop(): _Node<T> | null {
5050
// remove last node from list
51-
// O(n) time since we have to iterate over the whole list to find the new tail, and make the new tail's next point to null.
51+
// O(n) time since we have to iterate over the whole list to find the new tail,
52+
// and make the new tail's next point to null.
5253
if (!this.head) return null;
5354
const node = this.head;
5455
if (!node.next) {
@@ -115,41 +116,38 @@ class SinglyLinkedList<T> {
115116
}
116117

117118
insert(value: T, index: number, options: ListMethodOptions = { prevEnabled: false }): _Node<T> | null {
119+
if (index === 0) return this.unshift(value);
120+
if (index === this.length) return this.push(value);
118121

119-
// would be nice to refactor out the prevEnabled parts to the DoublyLinkedList insert method,
120-
// but setting the prev props for surrounding nodes has to be done one way...
121-
// * this method should be cleaned up and reorganized anyways since it's too long.
122122
const { prevEnabled } = options;
123123
let newNode = new _Node(value);
124-
if (index === 0) {
125-
// insert as head node
126-
if (prevEnabled) newNode.prev = null;
127-
newNode.next = this.head;
128-
this.head = newNode;
129-
this._length++;
130-
return newNode;
131-
}
132-
else if (index === this.length) {
133-
// insert as tail node
134-
if (prevEnabled) newNode.prev = this.tail;
135-
this.tail!.next = newNode;
136-
this.tail = newNode;
137-
}
138-
else {
139-
const prevNode = this.get(index - 1);
140-
if (!prevNode) return null; // TODO: throw indexError ? user tried to insert at out of range index.
141-
// maybe move the out of bounds errors to top of function?
142-
const targetNode = prevNode.next;
143-
if (prevEnabled) {
144-
newNode.prev = prevNode;
145-
targetNode!.prev = newNode; // assert exists because ^ insert as new tail node is covered
146-
}
147-
prevNode.next = newNode;
148-
newNode.next = targetNode;
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+
// maybe move the out of bounds errors to top of function?
127+
const targetNode = prevNode.next;
128+
if (prevEnabled) {
129+
newNode.prev = prevNode;
130+
targetNode!.prev = newNode; // assert exists because ^ insert as new tail node is covered
149131
}
132+
prevNode.next = newNode;
133+
newNode.next = targetNode;
150134
this._length++;
151135
return newNode;
152136
}
153137
}
154138

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+
// }
151+
152+
155153
export default SinglyLinkedList;

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