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Adrian333DevAdrian333Dev
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singly linked list
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‎implementations/linked_list/singly-linked-list.js‎

Lines changed: 141 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,141 @@
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class Node {
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constructor(val, next = null) {
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this.val = val;
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this.next = next;
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}
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}
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class LinkedList {
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constructor() {
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this.head = null;
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this.tail = null;
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this.length = 0;
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}
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/**
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* @param {number} index
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* @return {number}
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*/
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get(index) {
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if (index >= this.length || index < 0) return -1;
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if (index === this.length - 1) return this.tail.val;
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if (index === 0) return this.head.val;
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let curr = this.head;
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while (index-- > 0) (curr = curr.next);
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return curr.val;
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}
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insertToEmptyList(val) {
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this.head = new Node(val);
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this.tail = this.head;
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this.length++;
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}
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rmFromEmptyList(val) {
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this.head = null;
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this.tail = null;
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this.length = 0;
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return true;
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}
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/**
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* @param {number} val
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* @return {void}
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*/
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insertHead(val) {
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if (!this.length) this.insertToEmptyList(val);
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else (this.head = new Node(val, this.head)), this.length++;
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}
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/**
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* @param {number} val
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* @return {void}
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*/
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insertTail(val) {
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if (!this.length) this.insertToEmptyList(val);
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else
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(this.tail.next = new Node(val)),
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(this.tail = this.tail.next),
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this.length++;
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}
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removeHead() {
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this.head = this.head.next;
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this.length--;
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return true;
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}
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removeTail() {
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let curr = this.head;
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while (curr.next.next) curr = curr.next;
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this.tail = curr;
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this.tail.next = null;
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this.length--;
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return true;
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}
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/**
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* @param {number} index
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* @return {boolean}
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*/
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remove(index) {
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if (!this.length || index >= this.length) return false;
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if (this.length === 1) return this.rmFromEmptyList();
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if (index === 0) return this.removeHead();
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if (index === this.length - 1) return this.removeTail();
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let curr = this.head;
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while (index-- > 1) (curr = curr.next);
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curr.next = curr.next.next;
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this.length--;
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return true;
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}
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/**
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* @return {number[]}
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*/
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getValues() {
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let curr = this.head,
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values = [];
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while (curr) values.push(curr.val), (curr = curr.next);
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return values;
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}
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}
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// TESTS
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const test = (result, expected) => {
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if (result.length !== expected.length) return false;
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for (let i = 0; i < result.length; i++)
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if (result[i] !== expected[i]) return false;
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return true;
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};
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// ["insertTail", 1, "insertTail", 2, "get", 1, "remove", 1, "insertTail", 2, "get", 1, "get", 0]
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// const list = new LinkedList();
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// list.insertTail(1);
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// list.insertTail(2);
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// console.log(test(list.getValues(), [1, 2])); // true
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// console.log(list.get(1)); // 2
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// console.log(list.remove(1)); // true
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// list.insertTail(2);
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// console.log(list.get(1)); // 2
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// console.log(list.get(0)); // 1
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// console.log(test(list.getValues(), [1, 2])); // true
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// ["insertHead", 1, "insertHead", 2, "insertTail", 3, "insertTail", 4, "insertHead", 5, "get", 0, "get", 2, "get", 4, "remove", 2, "remove", 0, "insertHead", 6, "insertTail", 7, "getValues", "get", 5]
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const list = new LinkedList();
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list.insertHead(1);
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list.insertHead(2);
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list.insertTail(3);
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list.insertTail(4);
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list.insertHead(5);
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console.log(list.get(0)); // 5
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console.log(list.get(2)); // 3
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console.log(list.get(4)); // 4
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console.log(list.remove(2)); // true
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console.log(list.remove(0)); // true
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list.insertHead(6);
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list.insertTail(7);
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console.log(list.getValues()); // [6, 1, 3, 4, 7]
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console.log(list.get(5)); // 7

‎leetcode_30_days_js/02_compact-object.js‎

Lines changed: 46 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,46 @@
1+
/**
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* @param {Object|Array} obj
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* @return {Object|Array}
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*/
5+
6+
function arrHelper(arr) {
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let result = [];
8+
for (let val of arr) {
9+
if (val === null) continue;
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if (Array.isArray(val)) result.push(arrHelper(val));
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else if (typeof val === 'object') result.push(objHelper(val));
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else if (Boolean(val)) result.push(val);
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}
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return result;
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}
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function objHelper(obj) {
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let result = {};
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for (let key of Object.keys(obj)) {
20+
const val = obj[key];
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if (val === null) continue;
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if (Array.isArray(val)) result[key] = arrHelper(val);
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else if (typeof val === 'object') result[key] = objHelper(val);
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else if (Boolean(val)) result[key] = val;
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}
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return result;
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}
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const compactObject = (arrOrObj) => {
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if (Array.isArray(arrOrObj)) return arrHelper(arrOrObj);
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if (typeof arrOrObj === 'object') return objHelper(arrOrObj);
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};
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// TEST
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36+
console.log(
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compactObject({
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a: 1,
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b: null,
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c: 'hello',
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d: false,
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e: undefined,
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f: 0,
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g: 2,
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})
46+
); // { a: 1, c: 'hello', g: 2 }

‎neetcode_practice_150/04-stack/01_valid-parentheses.js‎

Lines changed: 16 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -2,19 +2,26 @@
22
* @param {string} s
33
* @return {boolean}
44
*/
5-
const isValid = function (s) {
6-
const pairs = { ')': '(', ']': '[', '}': '{' }, stack = [];
7-
for (let c of s)
8-
c in pairs
9-
? stack[stack.length - 1] === pairs[c]
10-
? stack.pop()
11-
: false
12-
: stack.push(c);
13-
return !stack.length;
5+
const isValid = (str) => {
6+
const pairs = {
7+
'(': ')',
8+
'{': '}',
9+
'[': ']',
10+
};
11+
const stack = [];
12+
for (let c of str) {
13+
if (c in pairs) stack.push(c);
14+
else if (pairs[stack[stack.length - 1]] === c) stack.pop();
15+
else return false;
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}
17+
18+
return stack.length === 0;
1419
};
1520

1621
// test
1722
console.log(isValid('()')); // true
1823
console.log(isValid('()[]{}')); // true
1924
console.log(isValid('(]')); // false
2025
console.log(isValid('([)]')); // false
26+
console.log(isValid('{[]}')); // true
27+
console.log(isValid('[')); // false

‎neetcode_practice_150/04-stack/02_min-stack.js‎

Lines changed: 44 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,41 @@ class MinStack {
44
this.minStack = [];
55
}
66

7+
/**
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* @param {number} val
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* @return {void}
10+
*/
11+
push(val) {
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if (!this.stack.length) this.stack.push(val), this.minStack.push(val);
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else {
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this.stack.push(val);
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if (this.getMin() > val) this.minStack.push(val);
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else this.minStack.push(this.getMin());
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}
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}
19+
20+
/**
21+
* @return {void}
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*/
23+
pop() {
24+
if (this.stack.length) this.stack.pop(), this.minStack.pop();
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}
26+
27+
/**
28+
* @return {number}
29+
*/
30+
top() {
31+
let len = this.stack.length;
32+
return len ? this.stack[len - 1] : null;
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}
34+
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/**
36+
* @return {number}
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*/
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getMin() {
39+
return this.minStack[this.minStack.length - 1];
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}
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742
print() {
843
console.log('stack:', this.stack.join(', '));
944
console.log('minStack:', this.minStack.join(', '));
@@ -16,24 +51,13 @@ class MinStack {
1651
// [[],[-2],[0],[-3],[],[],[],[]]
1752

1853
const minStack = new MinStack();
19-
// minStack.push(-2);
20-
// minStack.push(0);
21-
// minStack.push(-3);
22-
// minStack.print(); // stack: -2, 0, -3; minStack: -2, -3
23-
// console.log(minStack.getMin()); // -3
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// console.log(minStack.pop()); // -3
25-
// console.log(minStack.top()); // 0
26-
// console.log(minStack.getMin()); // -2
27-
// minStack.print(); // stack: -2, 0; minStack: -2
28-
29-
// ["MinStack","push","push","push","getMin","pop","getMin"]
30-
// [[],[0],[1],[0],[],[],[]]
31-
54+
minStack.push(-2);
3255
minStack.push(0);
33-
minStack.push(1);
34-
minStack.push(0);
35-
minStack.print(); // stack: 0, 1, 0; minStack: 0, 0
36-
console.log(minStack.getMin()); // 0
37-
console.log(minStack.pop()); // 0
38-
console.log(minStack.getMin()); // 0
39-
minStack.print(); // stack: 0, 1; minStack: 0
56+
minStack.push(-3);
57+
minStack.print();
58+
console.log(minStack.getMin());
59+
minStack.pop();
60+
minStack.print();
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console.log(minStack.top());
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console.log(minStack.getMin());
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