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Chahat Tekwani 2021-08-31 14:34:15 +05:30
parent 4548296aff
commit d19588e3da
1 changed files with 59 additions and 59 deletions
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118
src/data-structures/stack/Stack.js
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@ -1,67 +1,67 @@
import LinkedList from '../linked-list/LinkedList'; // import LinkedList from '../linked-list/LinkedList';
export default class Stack { // export default class Stack {
constructor() { // constructor() {
// We're going to implement Stack based on LinkedList since these // // We're going to implement Stack based on LinkedList since these
// structures are quite similar. Compare push/pop operations of the Stack // // structures are quite similar. Compare push/pop operations of the Stack
// with prepend/deleteHead operations of LinkedList. // // with prepend/deleteHead operations of LinkedList.
this.linkedList = new LinkedList(); // this.linkedList = new LinkedList();
} // }
/** // /**
* @return {boolean} // * @return {boolean}
*/ // */
isEmpty() { // isEmpty() {
// The stack is empty if its linked list doesn't have a head. // // The stack is empty if its linked list doesn't have a head.
return !this.linkedList.head; // return !this.linkedList.head;
} // }
/** // /**
* @return {*} // * @return {*}
*/ // */
peek() { // peek() {
if (this.isEmpty()) { // if (this.isEmpty()) {
// If the linked list is empty then there is nothing to peek from. // // If the linked list is empty then there is nothing to peek from.
return null; // return null;
} // }
// Just read the value from the start of linked list without deleting it. // // Just read the value from the start of linked list without deleting it.
return this.linkedList.head.value; // return this.linkedList.head.value;
} // }
/** // /**
* @param {*} value // * @param {*} value
*/ // */
push(value) { // push(value) {
// Pushing means to lay the value on top of the stack. Therefore let's just add // // Pushing means to lay the value on top of the stack. Therefore let's just add
// the new value at the start of the linked list. // // the new value at the start of the linked list.
this.linkedList.prepend(value); // this.linkedList.prepend(value);
} // }
/** // /**
* @return {*} // * @return {*}
*/ // */
pop() { // pop() {
// Let's try to delete the first node (the head) from the linked list. // // Let's try to delete the first node (the head) from the linked list.
// If there is no head (the linked list is empty) just return null. // // If there is no head (the linked list is empty) just return null.
const removedHead = this.linkedList.deleteHead(); // const removedHead = this.linkedList.deleteHead();
return removedHead ? removedHead.value : null; // return removedHead ? removedHead.value : null;
} // }
/** // /**
* @return {*[]} // * @return {*[]}
*/ // */
toArray() { // toArray() {
return this.linkedList // return this.linkedList
.toArray() // .toArray()
.map((linkedListNode) => linkedListNode.value); // .map((linkedListNode) => linkedListNode.value);
} // }
/** // /**
* @param {function} [callback] // * @param {function} [callback]
* @return {string} // * @return {string}
*/ // */
toString(callback) { // toString(callback) {
return this.linkedList.toString(callback); // return this.linkedList.toString(callback);
} // }
} // }