The Remove Duplicates from Sorted Array problem asks us to take a sorted array of integers and remove duplicate values in-place so that each unique value appears only once. The result must use the initial part of the array to store unique elements, and the rest of the array beyond…
Validate Binary Search Tree – 89. LeetCode
You’re given a binary tree, which is a structure where every node has at most two child nodes (left and right). Your task is to check if this tree is a Binary Search Tree. To be a valid BST, the tree must follow these rules: Think of it as ensuring…
Valid Mountain Array – 941. LeetCode
Imagine you are hiking on a mountain trail, where the path first climbs up to a peak and then descends. To check if the trail is a “valid mountain”, the path must strictly go up and then strictly go down, with no flat or repeated sections. This problem determines whether…
Combination Sum – 39. LeetCode
Imagine you’re given a list of numbers and a target value. You need to figure out all the unique ways to combine these numbers so their total equals the target. You can use any number as many times as you want, but the order of numbers in the combination does…
Longest Substring Without Repeating Characters – 3. LeetCode
Imagine you’re reading a sentence and trying to find the longest stretch of letters where no letter is repeated. The goal is to figure out the maximum length of such a stretch of unique characters without having to go through every possible combination. Brute Force Approach Optimal Approach Algorithm &…
Median Two Sorted Arrays – 4. LeetCode
Imagine you have two lists of numbers that are already sorted in order. You want to combine them and find the middle number (or the average of the two middle numbers if the total count is even). This middle value is called the “median”. The challenge is to do this…
Next Greater Element I – 496. LeetCode
Imagine you have two lists of numbers. For each number in the first list, you want to find the next larger number in the second list that comes after it. If no such number exists, you return -1. This problem is about efficiently finding these “next greater elements”. Brute Force…
Koko Eating Bananas – 875. LeetCode
Koko, a monkey, loves bananas. She has a pile of banana stacks and wants to eat all of them within H hours. She can only eat a fixed number of bananas per hour. The goal is to determine the minimum eating speed (bananas per hour) that allows her to finish…
Online Stock Span – 901. LeetCode
The “Online Stock Span” problem involves calculating the stock span, which the number of consecutive days (including today) a stock’s price was less than or equal to its current price. For example, if the stock price today is higher than the last three days, the span is four. It’s like…
Daily Temperatures – 739. LeetCode
The problem Daily Temperatures asks you to analyze a list of daily temperatures and determine, for each day, how many days you need to wait to see a warmer temperature. If no warmer day exists in the future, the result for that day is 0. For example, given temperatures like…
