Solutions

Valid Palindrome II Easy Valid Word Abbreviation Easy Merge Strings Alternately Easy Merge Sorted Array Easy Merge Two 2D Arrays by Summing Values Easy Move Zeroes Easy Remove Duplicates From Sorted Array Easy Squares of a Sorted Array Easy Assign Cookies Easy Find First Palindromic String in the Array Easy Sort Array by Parity Easy Reverse Words in a String III Easy Backspace String Compare Easy Check If Two String Arrays are Equivalent Easy Apply Operations to an Array Easy Adding Spaces to a String Medium Remove Duplicates From Sorted Array II Medium Partition Array According to Given Pivot Medium Two Sum II Input Array Is Sorted Medium 3Sum Medium 4Sum Medium Rotate Array Medium Container With Most Water Medium Number of Subsequences That Satisfy The Given Sum Condition Medium Array With Elements Not Equal to Average of Neighbors Medium Divide Players Into Teams of Equal Skill Medium Boats to Save People Medium K-th Symbol in Grammar Medium Minimum Time To Make Rope Colorful Medium Rearrange Array Elements by Sign Medium Bag of Tokens Medium Minimum Length of String after Deleting Similar Ends Medium Sentence Similarity III Medium Trapping Rain Water Hard

Sliding Window

Contains Duplicate II Easy Best Time to Buy And Sell Stock Easy Minimum Recolors to Get K Consecutive Black Blocks Easy Minimum Difference Between Highest And Lowest of K Scores Easy Number of Sub Arrays of Size K and Avg Greater than or Equal to Threshold Medium Grumpy Bookstore Owner Medium Alternating Groups II Medium Longest Substring Without Repeating Characters Medium Longest Repeating Character Replacement Medium Permutation In String Medium Frequency of The Most Frequent Element Medium Fruits into Basket Medium Maximum Number of Vowels in a Substring of Given Length Medium Minimum Number of Flips to Make The Binary String Alternating Medium Defuse the Bomb Easy Minimum Size Subarray Sum Medium Find K Closest Elements Medium Minimum Operations to Reduce X to Zero Medium Get Equal Substrings Within Budget Medium Number of Substrings Containing All Three Characters Medium Binary Subarrays with Sum Medium Count Number of Nice Subarrays Medium Subarray Product Less Than K Medium Find the Power of K-Size Subarrays I Medium Maximum Sum of Distinct Subarrays With Length K Medium Length of Longest Subarray With at Most K Frequency Medium Count Subarrays Where Max Element Appears at Least K Times Medium Maximum Beauty of an Array After Applying Operation Medium Take K of Each Character From Left and Right Medium Count of Substrings Containing Every Vowel and K Consonants II Medium Minimum Window Substring Hard Sliding Window Maximum Hard Subarrays with K Different Integers Hard Minimum Number of Operations to Make Array Continuous Hard Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit Medium Smallest Range Covering Elements from K Lists Hard

Stack

Crawler Log Folder Easy Baseball Game Easy Valid Parentheses Easy Implement Stack Using Queues Easy Implement Queue using Stacks Easy Final Prices With a Special Discount in a Shop Easy Make The String Great Easy Min Stack Medium Evaluate Reverse Polish Notation Medium Removing Stars From a String Medium Validate Stack Sequences Medium Asteroid Collision Medium Daily Temperatures Medium Online Stock Span Medium Car Fleet Medium Simplify Path Medium Decode String Medium Remove K Digits Medium Remove All Adjacent Duplicates In String II Medium Reverse Substrings Between Each Pair of Parentheses Medium Minimum String Length After Removing Substrings Easy Clear Digits Easy Minimum Add to Make Parentheses Valid Medium Maximum Width Ramp Medium 132 Pattern Medium Flatten Nested List Iterator Medium Sum of Subarray Minimums Medium Maximum Frequency Stack Hard Robot Collisions Hard Largest Rectangle In Histogram Hard Shortest Subarray with Sum at Least K Hard Parsing A Boolean Expression Hard Number of Atoms Hard

Binary Search

Binary Search Easy Search Insert Position Easy Guess Number Higher Or Lower Easy Arranging Coins Easy Valid Perfect Square Easy Sqrt(x) Easy Single Element in a Sorted Array Medium Find Peak Element Medium Successful Pairs of Spells and Potions Medium Search a 2D Matrix Medium Koko Eating Bananas Medium Capacity to Ship Packages Within D Days Medium Maximum Candies Allocated to K Children Medium House Robber IV Medium Minimize the Maximum Difference of Pairs Medium Minimized Maximum of Products Distributed to Any Store Medium Minimum Limit of Balls in a Bag Medium Minimum Time to Repair Cars Medium Find Minimum In Rotated Sorted Array Medium Search In Rotated Sorted Array Medium Search In Rotated Sorted Array II Medium Time Based Key Value Store Medium Find First And Last Position of Element In Sorted Array Medium Maximum Number of Removable Characters Medium Most Beautiful Item for Each Query Medium Search Suggestions System Medium Count the Number of Fair Pairs Medium Split Array Largest Sum Hard Find K-th Smallest Pair Distance Hard Median of Two Sorted Arrays Hard Find in Mountain Array Hard

Linked List

Reverse Linked List Easy Merge Two Sorted Lists Easy Linked List Cycle Easy Palindrome Linked List Easy Remove Linked List Elements Easy Remove Duplicates From Sorted List Easy Middle of the Linked List Easy Intersection of Two Linked Lists Easy Merge in Between Linked Lists Medium Merge Nodes in Between Zeros Medium Find the Minimum and Maximum Number of Nodes Between Critical Points Medium Remove Nodes From Linked List Medium Reorder List Medium Maximum Twin Sum Of A Linked List Medium Remove Nth Node From End of List Medium Delete Nodes From Linked List Present in Array Medium Swapping Nodes in a Linked List Medium Copy List With Random Pointer Medium Design Linked List Medium Design Browser History Medium Add Two Numbers Medium Find The Duplicate Number Medium Swap Nodes In Pairs Medium Sort List Medium Partition List Medium Rotate List Medium Reverse Linked List II Medium Design Circular Queue Medium Insertion Sort List Medium Split Linked List in Parts Medium LRU Cache Medium LFU Cache Hard Merge K Sorted Lists Hard Reverse Nodes In K Group Hard

Trees

Binary Tree Inorder Traversal Easy Binary Tree Preorder Traversal Easy Binary Tree Postorder Traversal Easy N-ary Tree Postorder Traversal Easy Invert Binary Tree Easy Maximum Depth of Binary Tree Easy Diameter of Binary Tree Easy Balanced Binary Tree Easy Same Tree Easy Subtree of Another Tree Easy Convert Sorted Array to Binary Search Tree Easy Merge Two Binary Trees Easy Path Sum Easy Range Sum of BST Easy Leaf-Similar Trees Easy Evaluate Boolean Binary Tree Easy Create Binary Tree From Descriptions Medium Populating Next Right Pointers In Each Node Medium Binary Tree Vertical Order Traversal Medium Construct String From Binary Tree Medium Lowest Common Ancestor of a Binary Search Tree Medium Insert into a Binary Search Tree Medium Delete Node in a BST Medium Binary Tree Level Order Traversal Medium Binary Tree Right Side View Medium Reverse Odd Levels of Binary Tree Medium Minimum Number of Operations to Sort a Binary Tree by Level Medium

2751. Robot Collisions - Explanation

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