The “Length of Last Word” problem asks us to find the length of the last word in a given string. A word is defined as a maximal substring consisting only of non-space characters. The problem may involve handling edge cases like multiple trailing spaces or no words at all. It…

The Binary Tree Right Side View problem asks us to return the nodes that are visible when a binary tree is viewed from its right side. Imagine standing to the right of a tree and looking at it: you can only see the rightmost nodes of each level. This problem…

Constructing a binary tree from its preorder and inorder traversals involves rebuilding the tree using the order in which nodes are visited. Preorder traversal visits the root node first, followed by the left and right subtrees, while inorder traversal visits the left subtree, root, and then the right subtree. By…

You are given a list of daily temperatures. For each day, you need to figure out how many days you must wait until the temperature becomes warmer. If there’s no future day with a warmer temperature, just put 0 for that day. The result will be a new list showing…

The “Remove Nth Node From End of List” problem asks you to remove the nth node from the end of a singly linked list. Think of it as counting backwards in a list of items and removing the specific one you’re pointing at. This involves understanding how to traverse and…

The “Generate Parentheses” problem is about creating all possible valid combinations of n pairs of parentheses. This problem is more about creativity and structure than raw computation—it involves figuring out how to place opening and closing parentheses such that the resulting sequence is valid. In order for sequences to be…

The Zigzag Conversion problem is all about rearranging a string into a zigzag pattern across several rows and then reading it line by line to create a new string. 2. Read row by row 3. Resulting string Optimal Algorithm: Row-by-Row Construction with Constant Space • Pattern: Simulated row traversal. •…

The “Word Pattern” problem involves checking if a given pattern string matches a sequence of words. Each character in the pattern corresponds to a word in the sequence, and the mapping between them must be consistent: no two characters can map to the same word, and no character can map…

The Search a 2D Matrix problem involves finding a target value. The matrix has two key properties: This structure makes the matrix conceptually similar to a 1D sorted array. The goal is to determine if the target exists in the matrix efficiently. Brute Force Approach Optimal Approach: Binary Search Algorithmic…

The Majority Element problem asks you to find the element that appears more than n/2 times in an array of size n. This element is guaranteed to exist. For example, in the array [3, 3, 4, 2, 3, 3, 5, 3], the majority element is 3 because it appears more…