Add two numbers represented as linked lists. Handle carry when sum > 9. Time complexity: O(max(N, M)), space complexity: O(max(N, M)).

Implementing MinStack in JavaScript: Use an auxiliary stack (minStack) to store the minimum element at each step, enabling O(1) time complexity for getMin(). Push and pop operations remain O(1).

We loop through chars of s, if its a closing bracket we compare with last element in stack, it should be appropriate as define in map otherwise we return false. JavaScript Code: https://example.com/jscode

Merge Intervals: Sort balloons by start pos, merge overlaps with single arrow, update last interval on overlap. Min arrows = size of merged intervals list. Time: O(n log n), Space: O(n).

Grouping Anagrams using Sorting takes O(nlogn * m) time complexity, but can be optimized to O(n * m) with Hashmap by counting character frequencies.

JavaScript Map Basics: A Map stores key-value pairs & maintains insertion order. Use set(), get(), has(), delete() methods. Iterate with for...of or forEach(). Ideal for frequent updates & maintaining order.

Cell State Mapping in Game of Life algorithm: Alive (1), Dead (0), Transitional Values (2, 3). Rules: Cell remains alive with 2 or 3 neighbors, dies with < 2 or > 3. Dead cell becomes alive with exactly 3 neighbors.

Minimum Window Substring: Find min window in `s` containing all chars of `t`. Use sliding window approach with freq maps. Expand & shrink window to find smallest valid substring.

Optimize string length with `lengthOfLongestSubstring` function. Uses Set to track unique substrings and slide window approach for efficient solution.

Javascript Code: longestCommonPrefix function iterates through strings to find common prefix, trimming at first mismatch.

Check every char in s is present in t sequentially. If found, skip to next char in t. This code implements this idea.

Two approaches to move zeros in an array: Naive Approach with swapping and Two Pointer Approach. The latter is more efficient, incrementing the left pointer after placing a non-zero element at its position.

Three approaches to solve increasingTriplet problem: Brute Force (O(n^3)), Two Pointer, and Greedy. Greedy approach is most efficient with time complexity O(n).

Naive Approach: Reverse Words in String Reverse words in a string without built-in functions, using loops and arrays. Time Complexity O(n), Space Complexity O(n).

Three approaches to reverse vowels in a string: Naive, Regex, and Two Pointers. The Naive approach uses two loops, the Regex method uses `match` and `replace`, while the Two Pointers approach swaps vowels from start and end of string.

Unique Email Addresses problem solved! Convert email to localName + domainName, ignore '+' and '.' for unique emails. Use Set to count unique emails.

Math.max(...candies) saves 80% runtime vs brute force solution, beating 88% of submissions!

Cannot complete courses due to loop in prerequisites. Use DFS to detect loops and return false. Example: [[1,0],[0,1]] has a loop, cannot complete 2 courses.

Merge two strings by alternating characters: `mergeAlternately` function takes two strings, iterates through each character, and returns a new string with chars from both inputs.