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Commit 4aa3204

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Chore: All Activites completed for Day-21
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‎Day21/Task.md

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@@ -5,28 +5,28 @@ Welcome to Day 21! Today, we're tackling some classic problems on LeetCode. Thes
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## Tasks/Activities 📝
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### Activity 1: Two Sum ➕
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- [] **Task 1:** Solve the "Two Sum" problem on LeetCode.
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- [X] **Task 1:** Solve the "Two Sum" problem on LeetCode.
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- Write a function that takes an array of numbers and a target number, and returns the indices of the two numbers that add up to the target.
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- Log the indices for a few test cases.
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### Activity 2: Reverse Integer 🔄
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- [] **Task 2:** Solve the "Reverse Integer" problem on LeetCode.
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- [X] **Task 2:** Solve the "Reverse Integer" problem on LeetCode.
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- Write a function that takes an integer and returns it with its digits reversed.
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- Handle edge cases like negative numbers and numbers ending in zero.
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- Log the reversed integers for a few test cases.
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### Activity 3: Palindrome Number 🔢
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- [] **Task 3:** Solve the "Palindrome Number" problem on LeetCode.
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- [X] **Task 3:** Solve the "Palindrome Number" problem on LeetCode.
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- Write a function that takes an integer and returns `true` if it is a palindrome, and `false` otherwise.
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- Log the result for a few test cases, including edge cases like negative numbers.
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### Activity 4: Merge Two Sorted Lists 🔗
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- [] **Task 4:** Solve the "Merge Two Sorted Lists" problem on LeetCode.
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- [X] **Task 4:** Solve the "Merge Two Sorted Lists" problem on LeetCode.
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- Write a function that takes two sorted linked lists and returns a new sorted list by merging them.
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- Create a few test cases with linked lists and log the merged list.
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### Activity 5: Valid Parentheses ✔️❌
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- [] **Task 5:** Solve the "Valid Parentheses" problem on LeetCode.
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- [X] **Task 5:** Solve the "Valid Parentheses" problem on LeetCode.
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- Write a function that takes a string containing just the characters '(', ')', '[', ']', '{', '}', and determines if the input string is valid.
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- A string is valid if open brackets are closed in the correct order.
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- Log the result for a few test cases.

‎Day21/index.js

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@@ -1,22 +1,177 @@
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console.log("-------------------------------------------------");
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console.log("Activity 1: ");
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// Task 1: Solve the "Two Sum" problem on LeetCode.
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// Write a function that takes an array of numbers and a target number, and returns the indices of the two numbers that add up to the target.
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// Log the indices for a few test cases.
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function twoSum(nums, target) {
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const map = new Map();
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for (let i = 0; i < nums.length; i++) {
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const complement = target - nums[i];
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if (map.has(complement)) {
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return [map.get(complement), i];
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}
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map.set(nums[i], i);
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}
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return [];
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}
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console.log(twoSum([2, 7, 11, 15], 9));
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console.log(twoSum([3, 2, 4], 6));
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console.log(twoSum([3, 3], 6));
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console.log(twoSum([1, 5, 3, 4], 8));
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console.log("-------------------------------------------------");
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console.log("Activity 2: ");
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// Task 2: Solve the "Reverse Integer" problem on LeetCode.
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// Write a function that takes an integer and returns it with its digits reversed.
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// Handle edge cases like negative numbers and numbers ending in zero.
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// Log the reversed integers for a few test cases.
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function reverseInteger(x) {
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const isNegative = x < 0;
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let reversed = parseInt(Math.abs(x).toString().split('').reverse().join(''));
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if (reversed > 2**31 - 1) {
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return 0;
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}
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return isNegative ? -reversed : reversed;
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}
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console.log(reverseInteger(123));
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console.log(reverseInteger(-123));
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console.log(reverseInteger(120));
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console.log(reverseInteger(0));
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console.log(reverseInteger(1534236469));
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console.log("-------------------------------------------------");
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console.log("Activity 3: ");
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// Task 3: Solve the "Palindrome Number" problem on LeetCode.
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// Write a function that takes an integer and returns true if it is a palindrome, and false otherwise.
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// Log the result for a few test cases, including edge cases like negative numbers.
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function isPalindrome(x) {
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if (x < 0) return false;
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const str = x.toString();
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return str === str.split('').reverse().join('');
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}
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console.log(isPalindrome(101));
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console.log(isPalindrome(1012));
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console.log(isPalindrome(10070010));
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console.log(isPalindrome(23456543));
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console.log("-------------------------------------------------");
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console.log("Activity 4: ");
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// Task 4: Solve the "Merge Two Sorted Lists" problem on LeetCode.
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// Write a function that takes two sorted linked lists and returns a new sorted list by merging them.
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// Create a few test cases with linked lists and log the merged list.
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class ListNode {
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constructor(val = 0, 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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function mergeTwoLists(l1, l2) {
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const dummy = new ListNode();
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let current = dummy;
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while (l1 !== null && l2 !== null) {
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if (l1.val < l2.val) {
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current.next = l1;
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l1 = l1.next;
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} else {
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current.next = l2;
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l2 = l2.next;
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}
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current = current.next;
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}
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// Attach the remaining nodes
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current.next = l1 !== null ? l1 : l2;
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return dummy.next;
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}
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// function to create a linked list from an array
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function createLinkedList(arr) {
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let head = new ListNode(arr[0]);
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let current = head;
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for (let i = 1; i < arr.length; i++) {
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current.next = new ListNode(arr[i]);
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current = current.next;
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}
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return head;
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}
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// Helper function to print linked list as an array
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function printLinkedList(head) {
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const result = [];
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while (head !== null) {
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result.push(head.val);
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head = head.next;
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}
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return result;
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}
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const list1 = createLinkedList([1, 2, 4]);
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const list2 = createLinkedList([1, 3, 4]);
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const mergedList = mergeTwoLists(list1, list2);
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console.log(printLinkedList(mergedList));
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const list3 = createLinkedList([5, 6, 7]);
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const list4 = createLinkedList([1, 2, 8]);
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const mergedList2 = mergeTwoLists(list3, list4);
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console.log(printLinkedList(mergedList2));
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const list5 = createLinkedList([]);
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const list6 = createLinkedList([0]);
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const mergedList3 = mergeTwoLists(list5, list6);
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console.log(printLinkedList(mergedList3));
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console.log("-------------------------------------------------");
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console.log("Activity 5: ");
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console.log("Activity 5: ");
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// Task 5: Solve the "Valid Parentheses" problem on LeetCode.
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// Write a function that takes a string containing just the characters '(', ')', '[', ']', '{', '}', and determines if the input string is valid.
147+
// A string is valid if open brackets are closed in the correct order.
148+
// Log the result for a few test cases.
149+
150+
function isValid(s) {
151+
const stack = [];
152+
const map = {
153+
')': '(',
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']': '[',
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'}': '{'
156+
};
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for (let char of s) {
159+
if (char === '(' || char === '[' || char === '{') {
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stack.push(char);
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} else if (stack.length > 0 && stack[stack.length - 1] === map[char]) {
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stack.pop();
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} else {
164+
return false;
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}
166+
}
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return stack.length === 0;
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}
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console.log(isValid("()"));
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console.log(isValid("()[]{}"));
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console.log(isValid("(]"));
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console.log(isValid("([)]"));
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console.log(isValid("{[]}"));
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console.log("-------------------------------------------------");

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