15.3 Lookup by Chapter

Chapter	Problem	Platform	Problem ID	Difficulty
Array	Two Sums I	LeetCode	1	Easy
Array	Median of Two Sorted Arrays	LeetCode	4	Hard
Array	Container With Most Water	LeetCode	11	Medium
Array	3Sum	LeetCode	15	Medium
Array	3Sum Closest	LeetCode	16	Medium
Array	4Sum	LeetCode	18	Medium
Array	Remove Duplicates from Sorted Array	LeetCode	26	Easy
Array	Search in Rotated Sorted Array	LeetCode	33	Medium
Array	Maximum Subarray	LeetCode	53	Easy
Array	Merge Intervals	LeetCode	56	Medium
Array	Insert Interval	LeetCode	57	Hard
Array	Plus One	LeetCode	66	Easy
Array	Sort Colors	LeetCode	75	Medium
Array	Best Time to Buy and Sell Stock	LeetCode	121	Easy
Array	Best Time to Buy and Sell Stock II	LeetCode	122	Easy
Array	Gas Station	LeetCode	134	Medium
Array	Maximum Product Subarray	LeetCode	152	Medium
Array	Two Sum II - Sorted Array	LeetCode	167	Medium
Array	Minimum Size Subarray Sum	LeetCode	209	Medium
Array	Product of Array Except Self	LeetCode	238	Medium
Array	Find the Duplicate Number	LeetCode	287	Medium
Array	Random Pick Index	LeetCode	398	Medium
Array	Non-overlapping Intervals	LeetCode	435	Medium
Array	4Sum II	LeetCode	454	Medium
Array	Random Pick with Weight	LeetCode	528	Medium
Array	Binary Search	LeetCode	704	Easy
Array	Hand of Straights	LeetCode	846	Medium
Array	Maximize Distance to Closest Person	LeetCode	849	Medium
Array	Koko Eating Bananas	LeetCode	875	Medium
Array	Sort Array By Parity	LeetCode	905	Easy
Array	Interval List Intersections	LeetCode	986	Medium
Array	Find Common Characters	LeetCode	1002	Easy
Array	Cutting Ribbons	LeetCode	1891	Medium
Array	Merge Triplets to Form Target Triplet	LeetCode	1899	Medium
Array	Eliminate Maximum Monsters	LeetCode	1921	Medium
Array	Number of Zero-Filled Subarrays	LeetCode	2348	Medium
Array	Divide Array Into Arrays With Max Difference	LeetCode	2966	Medium
Array	Minimum Operations to Make Binary Array Elements Equal to One I	LeetCode	3191	Medium
Array	Shortest Word Distance	LeetCode	-	Easy
Array	Count Elements Greater Than Previous Average	HackerRank	-	Easy
Array	Count Number Pairs	HackerRank	-	Easy
Array	Merge and Sort Intervals	HackerRank	-	Medium
Array	Max Gain	Firecode	-	Easy
Array	Maximum Number of Repetitions	Firecode	-	Medium
Array	Selection Sort Array	Firecode	-	Easy
Array	Two Sum II - Boolean	Other	-	Easy
Array	Two Sum V	Other	-	Medium
Array	Retrieve Elements K Times	Other	-	Easy
Array	Quick Sort Array	Interview	-	Medium
Matrix	Valid Sudoku	LeetCode	36	Medium
Matrix	Rotate Image	LeetCode	48	Medium
Matrix	Spiral Matrix	LeetCode	54	Medium
Matrix	Set Matrix Zeroes	LeetCode	73	Medium
Matrix	Search a 2D Matrix	LeetCode	74	Medium
Matrix	Surrounded Regions	LeetCode	130	Medium
Matrix	Number of Islands	LeetCode	200	Medium
Matrix	Search a 2D Matrix II	LeetCode	240	Medium
Matrix	Walls and Gates	LeetCode	286	Medium
Matrix	Best Meeting Point	LeetCode	296	Hard
Matrix	Design Tic-Tac-Toe	LeetCode	348	Medium
Matrix	Pacific Atlantic Water Flow	LeetCode	417	Medium
Matrix	Battleships in a Board	LeetCode	419	Medium
Matrix	01 Matrix	LeetCode	542	Medium
Matrix	Brick Wall	LeetCode	554	Medium
Matrix	Rotting Oranges	LeetCode	994	Medium
Matrix	Detect Squares	LeetCode	2013	Medium
Tree	Binary Tree Inorder Traversal	LeetCode	94	Easy
Tree	Validate Binary Search Tree	LeetCode	98	Medium
Tree	Binary Tree Level Order Traversal	LeetCode	102	Medium
Tree	Binary Tree Level Order Traversal II	LeetCode	107	Medium
Tree	Balanced Binary Tree	LeetCode	110	Easy
Tree	Minimum Depth of Binary Tree	LeetCode	111	Easy
Tree	Path Sum	LeetCode	112	Easy
Tree	Populating Next Right Pointers in Each Node	LeetCode	116	Medium
Tree	Binary Tree Preorder Traversal	LeetCode	144	Easy
Tree	Binary Tree Postorder Traversal	LeetCode	145	Easy
Tree	Binary Tree Upside Down	LeetCode	156	Medium
Tree	Implement Trie (Prefix Tree)	LeetCode	208	Medium
Tree	Kth Smallest Element in a BST	LeetCode	230	Medium
Tree	Lowest Common Ancestor of a Binary Search Tree	LeetCode	235	Medium
Tree	Lowest Common Ancestor of a Binary Tree	LeetCode	236	Medium
Tree	Count Univalue Subtrees	LeetCode	250	Medium
Tree	Inorder Successor in BST	LeetCode	285	Medium
Tree	Serialize and Deserialize Binary Tree	LeetCode	297	Hard
Tree	Binary Tree Longest Consecutive Sequence	LeetCode	298	Medium
Tree	Find Leaves of Binary Tree	LeetCode	366	Medium
Tree	Diameter of Binary Tree	LeetCode	543	Easy
Tree	Subtree of Another Tree	LeetCode	572	Easy
Tree	Two Sum IV - BST	LeetCode	653	Easy
Tree	Count Good Nodes in Binary Tree	LeetCode	1448	Medium
Tree	Height of Binary Search Tree	HackerRank	-	Easy
Graph	Clone Graph	LeetCode	133	Medium
Graph	Course Schedule	LeetCode	207	Medium
Graph	Course Schedule II	LeetCode	210	Medium
Graph	Graph Valid Tree	LeetCode	261	Medium
Graph	Alien Dictionary	LeetCode	269	Hard
Graph	Number of Connected Components in an Undirected Graph	LeetCode	323	Medium
Graph	Accounts Merge	LeetCode	721	Medium
Graph	Network Delay Time	LeetCode	743	Medium
Graph	Distance of Nearest Cell Having 1	Other	-	Medium
Graph	Graph Serialization	Other	-	Unclassified
Graph	Hardware Build Feasibility	Interview	-	Medium
Linked List	Add Two Numbers	LeetCode	2	Medium
Linked List	Remove Nth Node From End	LeetCode	19	Medium
Linked List	Merge Two Sorted Lists	LeetCode	21	Easy
Linked List	Merge k Sorted Lists	LeetCode	23	Hard
Linked List	Reverse Nodes in k-Group	LeetCode	25	Hard
Linked List	Remove Duplicates from Sorted List	LeetCode	83	Easy
Linked List	Reverse Linked List II	LeetCode	92	Medium
Linked List	Copy List with Random Pointer	LeetCode	138	Medium
Linked List	Linked List Cycle	LeetCode	141	Easy
Linked List	Linked List Cycle II	LeetCode	142	Medium
Linked List	Reorder List	LeetCode	143	Medium
Linked List	Insertion Sort List	LeetCode	147	Medium
Linked List	Sort List	LeetCode	148	Medium
Linked List	Intersection of Two Linked Lists	LeetCode	160	Easy
Linked List	Reverse Linked List	LeetCode	206	Easy
Linked List	Palindrome Linked List	LeetCode	234	Easy
Linked List	Odd Even Linked List	LeetCode	328	Medium
Linked List	Merge In Between Linked Lists	LeetCode	1669	Medium
Linked List	One-Pass Removal of k-th Node from End	HackerRank	-	Medium
Linked List	Reverse Even-Indexed Nodes and Append	HackerRank	-	Medium
Linked List	Insert Node at Position in Doubly Linked List	Other	-	Easy
Stack and Queue	Longest Valid Parentheses	LeetCode	32	Hard
Stack and Queue	Evaluate Reverse Polish Notation	LeetCode	150	Medium
Stack and Queue	Min Stack	LeetCode	155	Medium
Stack and Queue	Implement Queue using Stacks	LeetCode	232	Easy
Stack and Queue	Task Scheduler	LeetCode	621	Medium
Stack and Queue	Daily Temperatures	LeetCode	739	Medium
Stack and Queue	Car Fleet	LeetCode	853	Medium
Stack and Queue	Maximum Score From Removing Substrings	LeetCode	1717	Medium
Stack and Queue	Validate Properly Nested Brackets	HackerRank	-	Easy
Stack and Queue	Next Greater Element with Position Offset	HackerRank	-	Medium
Stack and Queue	Lock-Free Stack Using Linked List (CAS)	Interview	-	Easy
Heap	Find kth Largest Element	LeetCode	215	Medium
Heap	Meeting Rooms II	LeetCode	253	Medium
Heap	Find Median from Data Stream	LeetCode	295	Hard
Heap	Top K Frequent Elements	LeetCode	347	Medium
Heap	K Closest Points to Origin	LeetCode	973	Medium
Heap	Last Stone Weight	LeetCode	1046	Easy
Heap	Top K Frequent Events with Order Preservation	HackerRank	-	Medium
Heap	Merge K Sorted Arrays	Interview	-	Medium
Heap	Top K Elements	Interview	-	Medium
Heap	VIP Customer Scheduler	Interview	-	Medium
String Manipulation	Longest Substring Without Repeating	LeetCode	3	Medium
String Manipulation	String to Integer (atoi)	LeetCode	8	Medium
String Manipulation	Longest Common Prefix	LeetCode	14	Easy
String Manipulation	Group Anagrams	LeetCode	49	Medium
String Manipulation	Word Ladder	LeetCode	127	Medium
String Manipulation	Design Add and Search Words Data Structure	LeetCode	211	Medium
String Manipulation	Encode and Decode Strings	LeetCode	271	Medium
String Manipulation	Ransom Note	LeetCode	383	Easy
String Manipulation	Longest Palindrome	LeetCode	409	Easy
String Manipulation	Longest Repeating Character Replacement	LeetCode	424	Medium
String Manipulation	Find All Anagrams in a String	LeetCode	438	Medium
String Manipulation	Sort Characters By Frequency	LeetCode	451	Medium
String Manipulation	Permutation in String	LeetCode	567	Medium
String Manipulation	Valid Palindrome II	LeetCode	680	Easy
String Manipulation	Verifying an Alien Dictionary	LeetCode	953	Easy
String Manipulation	Minimum Number of Steps to Make Two Strings Anagram	LeetCode	1347	Medium
String Manipulation	Number of Substrings All Three Chars	LeetCode	1358	Medium
String Manipulation	Check Palindrome by Filtering Non-Letters	HackerRank	-	Easy
String Manipulation	Max Unique Substring Length in a Session	HackerRank	-	Medium
String Manipulation	Binary Representation	Firecode	-	Easy
String Manipulation	Insert Stars	Firecode	-	Easy
String Manipulation	First Non-Repeated Character	Interview	-	Easy
Math	Reverse Integer	LeetCode	7	Medium
Math	Pow(x; n)	LeetCode	50	Medium
Math	Single Number	LeetCode	136	Easy
Math	Reverse Bits	LeetCode	190	Easy
Math	Number of 1 Bits	LeetCode	191	Easy
Math	Happy Number	LeetCode	202	Easy
Math	Count Primes	LeetCode	204	Easy
Math	Sum of Two Integers	LeetCode	371	Medium
Math	Implement Rand10() Using Rand7()	LeetCode	470	Medium
Math	Power of Two	Firecode	-	Easy
Interactive	First Bad Version	LeetCode	278	Easy
Interactive	Guess the Word	LeetCode	843	Hard
Advanced Data Structure	Design LRU Cache	LeetCode	146	Medium
Advanced Data Structure	Design Twitter	LeetCode	355	Medium
Advanced Data Structure	Design HashSet	LeetCode	705	Easy
Advanced Data Structure	Design HashMap	LeetCode	706	Easy
Advanced Data Structure	My Calendar I	LeetCode	729	Medium
Advanced Data Structure	Time Based Key-Value Store	LeetCode	981	Medium
Advanced Data Structure	Simple Bank System	LeetCode	2043	Medium
Advanced Data Structure	Implement Stack Using Queues	Interview	-	Easy
Advanced Data Structure	Implement Queue	Interview	-	Easy
Dynamic Programming and Backtracking	Longest Palindromic Substring	LeetCode	5	Medium
Dynamic Programming and Backtracking	Letter Combinations of a Phone Number	LeetCode	17	Medium
Dynamic Programming and Backtracking	Combination Sum	LeetCode	39	Medium
Dynamic Programming and Backtracking	Permutations	LeetCode	46	Medium
Dynamic Programming and Backtracking	Permutations II	LeetCode	47	Medium
Dynamic Programming and Backtracking	Unique Paths	LeetCode	62	Medium
Dynamic Programming and Backtracking	Minimum Path Sum	LeetCode	64	Medium
Dynamic Programming and Backtracking	Climbing Stairs	LeetCode	70	Easy
Dynamic Programming and Backtracking	Subsets	LeetCode	78	Medium
Dynamic Programming and Backtracking	Word Search	LeetCode	79	Medium
Dynamic Programming and Backtracking	Subsets II	LeetCode	90	Medium
Dynamic Programming and Backtracking	Decode Ways	LeetCode	91	Medium
Dynamic Programming and Backtracking	Pascal’s Triangle	LeetCode	118	Easy
Dynamic Programming and Backtracking	Word Break	LeetCode	139	Medium
Dynamic Programming and Backtracking	House Robber	LeetCode	198	Easy
Dynamic Programming and Backtracking	Maximal Square	LeetCode	221	Medium
Dynamic Programming and Backtracking	Paint House	LeetCode	256	Easy
Dynamic Programming and Backtracking	Longest Increasing Subsequence	LeetCode	300	Medium
Dynamic Programming and Backtracking	Best Time to Buy and Sell Stock with Cooldown	LeetCode	309	Medium
Dynamic Programming and Backtracking	Coin Change	LeetCode	322	Medium
Dynamic Programming and Backtracking	Coin Change II	LeetCode	518	Medium
Dynamic Programming and Backtracking	Palindromic Substrings	LeetCode	647	Medium
Dynamic Programming and Backtracking	Minimum Swaps Sequences Increasing	LeetCode	801	Medium
Dynamic Programming and Backtracking	Count Square Submatrices with All Ones	LeetCode	1277	Medium
Dynamic Programming and Backtracking	Find Index Combinations with Target Weight Sum	HackerRank	-	Medium
Dynamic Programming and Backtracking	Minimum Plans to Reach Target Bandwidth	HackerRank	-	Medium
Dynamic Programming and Backtracking	Generate Valid Angle Bracket Sequences	HackerRank	-	Easy
Dynamic Programming and Backtracking	Custom Fibonacci Sequence	HackerRank	-	Easy
Dynamic Programming and Backtracking	Retrieve Optimal Computation	Firecode	-	Medium
Dynamic Programming and Backtracking	Fibonacci Sequence	Firecode	-	Easy
Dynamic Programming and Backtracking	Longest Common Substring	Interview	-	Medium
Dynamic Programming and Backtracking	Minimum Operations to One	Interview	-	Medium

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