Today’s challenge was LeetCode – Zigzag Conversion, a great problem for practicing string manipulation, arrays, loops, and direction-based traversal in JavaScript. The problem gives us a string and a number of rows. We need to arrange the characters in a zigzag pattern and then read the characters row by row to generate the final string. For example: PAYPALISHIRING With numRows = 3, the character…
The goal is simple but interesting: given a string s, find the longest substring that reads the same forward and backward. For example: Input: "babad" Output: "bab" or "aba" 💡 Approach: Expand Around Center Instead of generating every possible substring and checking whether it is a palindrome, I used the Expand Around Center technique. Every palindrome has a center: Odd-length palindrome → one ch…
The goal is simple but requires a smart approach: given a string, find the length of the longest substring that contains no repeated characters. For example: "abcabcbb" → 3 ("abc") "bbbbb" → 1 ("b") "pwwkew" → 3 ("wke") Instead of checking every possible substring, I solved it using the Sliding Window + Hash Map technique. 💡 How the approach works I maintain two important variables: 🔹 start — rep…
The problem involves adding two numbers represented by linked lists, where each node contains a single digit. The digits are stored in reverse order, and the result must also be returned as a linked list. For example: Input: l1 = [2,4,3] l2 = [5,6,4] Output: [7,0,8] This problem may look simple at first, but it requires careful handling of several important concepts: 🔹 Linked List Traversal I lea…
