1. Problem Summary You are given the root of a binary tree where each node contains a value of either 0 or 1.Every path from the root to a leaf forms a binary number, where the digits are collected in the order they appear along the path. Your task is to compute the sum of…

You are given a pattern string (consisting of lowercase letters) and a sentence string made of words separated by spaces. Your task: Determine whether the sentence follows the same pattern, meaning: Example: Another example: Another: Another: Problem Understanding This problem is about bijective mapping: For the pattern to match: Logic Explained in Simple English Here’s…

You are given two binary square matrices img1 and img2 of size n x n, containing only 0s and 1s. Your task: Slide one image over the other (up, down, left, right) and determine the maximum number of overlapping 1’s. Example: Explanation:A shift exists that causes 3 overlapping 1s. Problem Understanding Key characteristics: Brute force…

You are given a square matrix mat of size n x n.Your task: Return the sum of the matrix’s primary diagonal and secondary diagonal. Example: Another example: Problem Understanding Important details: Key insight: For each row i, add: And avoid double-count when i == n – 1 – i. Logic Explained in Simple English The…

You are given the roots of two Binary Search Trees (BSTs): Your task: Return a sorted list containing all elements from both trees. Example: Another example: Problem Understanding Important characteristics: So the challenge reduces to: Extract sorted lists from both BSTs, then merge them. This is identical to merging two sorted arrays. Logic Explained in…

You are given a string s.Your task: Partition the string into as many pieces as possible such that each letter appears in at most one partition. Return a list containing the sizes of these partitions. Example: Another example: Problem Understanding Important characteristics: Key insight: A partition ends when the farthest last occurrence of all characters…

You are given a string s.Your task: Determine whether s can be constructed by repeating a substring multiple times. Examples: Problem Understanding We need to check: Does there exist a substring t such that: Observations: Better insight exists. Logic Explained in Simple English Here’s the cleanest way to think about it: Key idea: If a…

You are given an integer array nums, and two integers k and t. Your task: Determine whether there exist two distinct indices i and j such that: Example: Another example: Problem Understanding This problem mixes value closeness and index closeness: We need: Brute force would check all pairs within k distance for each index: We…

You are given an array of exactly four digits (each between 0 and 9). Your task: Construct the largest valid 24-hour time in the format “HH:MM” using all four digits exactly once. If it is not possible to form any valid time, return: Examples: Problem Understanding A valid 24-hour time must satisfy: Because digits must…

You are given an array nums of positive integers. Your task: Return the size of the largest connected component, where two numbers are connected if they share a common factor greater than 1. Example: Another example: Problem Understanding Two numbers belong to the same connected component if: This means it’s not enough to check pairwise…