Medium LeetCode Problems: Page 3 of 8

Problems 401 to 600 of the 1,579 Medium-rated problems in this library, continuing the list on the Medium hub.

Page 3 of 8

Medium problems, page 3
No.	Problem	Topics
0889	Construct Binary Tree from Preorder and Postorder Traversal	Tree, Array, Hash Table +2
0890	Find and Replace Pattern	Array, Hash Table, String
0893	Groups of Special-Equivalent Strings	Array, Hash Table, String +1
0894	All Possible Full Binary Trees	Tree, Recursion, Memoization +2
0898	Bitwise ORs of Subarrays	Bit Manipulation, Array, Dynamic Programming
0900	RLE Iterator	Design, Array, Counting +1
0901	Online Stock Span	Stack, Design, Data Stream +1
0904	Fruit Into Baskets	Array, Hash Table, Sliding Window
0907	Sum of Subarray Minimums	Stack, Array, Dynamic Programming +1
0909	Snakes and Ladders	Breadth-First Search, Array, Matrix
0910	Smallest Range II	Greedy, Array, Math +1
0911	Online Election	Design, Array, Hash Table +1
0912	Sort an Array	Array, Divide and Conquer, Bucket Sort +5
0915	Partition Array into Disjoint Intervals	Array
0916	Word Subsets	Array, Hash Table, String
0918	Maximum Sum Circular Subarray	Queue, Array, Divide and Conquer +2
0919	Complete Binary Tree Inserter	Tree, Breadth-First Search, Design +1
0921	Minimum Add to Make Parentheses Valid	Stack, Greedy, String
0923	3Sum With Multiplicity	Array, Hash Table, Two Pointers +2
0926	Flip String to Monotone Increasing	String, Dynamic Programming
0930	Binary Subarrays With Sum	Array, Hash Table, Prefix Sum +1
0931	Minimum Falling Path Sum	Array, Dynamic Programming, Matrix
0932	Beautiful Array	Array, Math, Divide and Conquer
0934	Shortest Bridge	Depth-First Search, Breadth-First Search, Array +1
0935	Knight Dialer	Dynamic Programming
0937	Reorder Data in Log Files	Array, String, Sorting
0939	Minimum Area Rectangle	Geometry, Array, Hash Table +2
0945	Minimum Increment to Make Array Unique	Greedy, Array, Counting +1
0946	Validate Stack Sequences	Stack, Array, Simulation
0947	Most Stones Removed with Same Row or Column	Depth-First Search, Union Find, Graph +1
0948	Bag of Tokens	Greedy, Array, Two Pointers +1
0949	Largest Time for Given Digits	Array, String, Backtracking +1
0950	Reveal Cards In Increasing Order	Queue, Array, Sorting +1
0951	Flip Equivalent Binary Trees	Tree, Depth-First Search, Binary Tree
0954	Array of Doubled Pairs	Greedy, Array, Hash Table +1
0955	Delete Columns to Make Sorted II	Greedy, Array, String
0958	Check Completeness of a Binary Tree	Tree, Breadth-First Search, Binary Tree
0959	Regions Cut By Slashes	Depth-First Search, Breadth-First Search, Union Find +3
0962	Maximum Width Ramp	Stack, Array, Two Pointers +1
0963	Minimum Area Rectangle II	Geometry, Array, Hash Table +1
0966	Vowel Spellchecker	Array, Hash Table, String
0967	Numbers With Same Consecutive Differences	Breadth-First Search, Backtracking
0969	Pancake Sorting	Greedy, Array, Two Pointers +1
0970	Powerful Integers	Hash Table, Math, Enumeration
0971	Flip Binary Tree To Match Preorder Traversal	Tree, Depth-First Search, Binary Tree
0973	K Closest Points to Origin	Geometry, Array, Math +4
0974	Subarray Sums Divisible by K	Array, Hash Table, Prefix Sum
0978	Longest Turbulent Subarray	Array, Dynamic Programming, Sliding Window
0979	Distribute Coins in Binary Tree	Tree, Depth-First Search, Binary Tree
0981	Time Based Key-Value Store	Design, Hash Table, String +1
0983	Minimum Cost For Tickets	Array, Dynamic Programming
0984	String Without AAA or BBB	Greedy, String
0985	Sum of Even Numbers After Queries	Array, Simulation
0986	Interval List Intersections	Array, Two Pointers, Line Sweep
0988	Smallest String Starting From Leaf	Tree, Depth-First Search, String +2
0990	Satisfiability of Equality Equations	Union Find, Graph, Array +1
0991	Broken Calculator	Greedy, Math
0994	Rotting Oranges	Breadth-First Search, Array, Matrix
0998	Maximum Binary Tree II	Tree, Binary Tree
1003	Check If Word Is Valid After Substitutions	Stack, String
1004	Max Consecutive Ones III	Array, Binary Search, Prefix Sum +1
1006	Clumsy Factorial	Stack, Math, Simulation
1007	Minimum Domino Rotations For Equal Row	Greedy, Array
1008	Construct Binary Search Tree from Preorder Traversal	Stack, Tree, Binary Search Tree +3
1010	Pairs of Songs With Total Durations Divisible by 60	Array, Hash Table, Counting
1011	Capacity To Ship Packages Within D Days	Array, Binary Search
1014	Best Sightseeing Pair	Array, Dynamic Programming
1015	Smallest Integer Divisible by K	Hash Table, Math
1016	Binary String With Substrings Representing 1 To N	Bit Manipulation, Hash Table, String +1
1017	Convert to Base -2	Math
1019	Next Greater Node In Linked List	Stack, Array, Linked List +1
1020	Number of Enclaves	Depth-First Search, Breadth-First Search, Union Find +2
1023	Camelcase Matching	Trie, Array, Two Pointers +2
1024	Video Stitching	Greedy, Array, Dynamic Programming
1026	Maximum Difference Between Node and Ancestor	Tree, Depth-First Search, Binary Tree
1027	Longest Arithmetic Subsequence	Array, Hash Table, Binary Search +1
1029	Two City Scheduling	Greedy, Array, Sorting
1031	Maximum Sum of Two Non-Overlapping Subarrays	Array, Dynamic Programming, Sliding Window
1033	Moving Stones Until Consecutive	Brainteaser, Math
1034	Coloring A Border	Depth-First Search, Breadth-First Search, Array +1
1035	Uncrossed Lines	Array, Dynamic Programming
1038	Binary Search Tree to Greater Sum Tree	Tree, Depth-First Search, Binary Search Tree +1
1039	Minimum Score Triangulation of Polygon	Array, Dynamic Programming
1040	Moving Stones Until Consecutive II	Array, Math, Sorting +1
1041	Robot Bounded In Circle	Math, String, Simulation
1042	Flower Planting With No Adjacent	Depth-First Search, Breadth-First Search, Graph
1043	Partition Array for Maximum Sum	Array, Dynamic Programming
1048	Longest String Chain	Array, Hash Table, Two Pointers +3
1049	Last Stone Weight II	Array, Dynamic Programming
1052	Grumpy Bookstore Owner	Array, Sliding Window
1053	Previous Permutation With One Swap	Greedy, Array
1054	Distant Barcodes	Greedy, Array, Hash Table +3
1061	Lexicographically Smallest Equivalent String	Union Find, String
1072	Flip Columns For Maximum Number of Equal Rows	Array, Hash Table, Matrix
1073	Adding Two Negabinary Numbers	Array, Math
1079	Letter Tile Possibilities	Hash Table, String, Backtracking +1
1080	Insufficient Nodes in Root to Leaf Paths	Tree, Depth-First Search, Binary Tree
1081	Smallest Subsequence of Distinct Characters	Stack, Greedy, String +1
1090	Largest Values From Labels	Greedy, Array, Hash Table +2
1091	Shortest Path in Binary Matrix	Breadth-First Search, Array, Matrix
1093	Statistics from a Large Sample	Array, Math, Probability and Statistics
1094	Car Pooling	Array, Prefix Sum, Sorting +2
1104	Path In Zigzag Labelled Binary Tree	Tree, Math, Binary Tree
1105	Filling Bookcase Shelves	Array, Dynamic Programming
1109	Corporate Flight Bookings	Array, Prefix Sum
1110	Delete Nodes And Return Forest	Tree, Depth-First Search, Array +2
1111	Maximum Nesting Depth of Two Valid Parentheses Strings	Stack, String
1115	Print FooBar Alternately	Concurrency
1116	Print Zero Even Odd	Concurrency
1117	Building H2O	Concurrency
1123	Lowest Common Ancestor of Deepest Leaves	Tree, Depth-First Search, Breadth-First Search +2
1124	Longest Well-Performing Interval	Stack, Array, Hash Table +2
1129	Shortest Path with Alternating Colors	Breadth-First Search, Graph
1130	Minimum Cost Tree From Leaf Values	Stack, Greedy, Array +2
1131	Maximum of Absolute Value Expression	Array, Math
1138	Alphabet Board Path	Hash Table, String
1139	Largest 1-Bordered Square	Array, Dynamic Programming, Matrix
1140	Stone Game II	Array, Math, Dynamic Programming +2
1143	Longest Common Subsequence	String, Dynamic Programming
1144	Decrease Elements To Make Array Zigzag	Greedy, Array
1145	Binary Tree Coloring Game	Tree, Depth-First Search, Binary Tree
1146	Snapshot Array	Design, Array, Hash Table +1
1155	Number of Dice Rolls With Target Sum	Dynamic Programming
1156	Swap For Longest Repeated Character Substring	Hash Table, String, Sliding Window
1161	Maximum Level Sum of a Binary Tree	Tree, Depth-First Search, Breadth-First Search +1
1162	As Far from Land as Possible	Breadth-First Search, Array, Dynamic Programming +1
1169	Invalid Transactions	Array, Hash Table, String +1
1170	Compare Strings by Frequency of the Smallest Character	Array, Hash Table, String +2
1171	Remove Zero Sum Consecutive Nodes from Linked List	Hash Table, Linked List
1177	Can Make Palindrome from Substring	Bit Manipulation, Array, Hash Table +2
1186	Maximum Subarray Sum with One Deletion	Array, Dynamic Programming
1190	Reverse Substrings Between Each Pair of Parentheses	Stack, String
1191	K-Concatenation Maximum Sum	Array, Dynamic Programming
1201	Ugly Number III	Math, Binary Search, Combinatorics +1
1202	Smallest String With Swaps	Depth-First Search, Breadth-First Search, Union Find +4
1208	Get Equal Substrings Within Budget	String, Binary Search, Prefix Sum +1
1209	Remove All Adjacent Duplicates in String II	Stack, String
1218	Longest Arithmetic Subsequence of Given Difference	Array, Hash Table, Dynamic Programming
1219	Path with Maximum Gold	Array, Backtracking, Matrix
1222	Queens That Can Attack the King	Array, Matrix, Simulation
1227	Airplane Seat Assignment Probability	Brainteaser, Math, Dynamic Programming +1
1233	Remove Sub-Folders from the Filesystem	Depth-First Search, Trie, Array +1
1234	Replace the Substring for Balanced String	String, Sliding Window
1237	Find Positive Integer Solution for a Given Equation	Math, Two Pointers, Binary Search +1
1238	Circular Permutation in Binary Representation	Bit Manipulation, Math, Backtracking
1239	Maximum Length of a Concatenated String with Unique Characters	Bit Manipulation, Array, String +1
1247	Minimum Swaps to Make Strings Equal	Greedy, Math, String
1248	Count Number of Nice Subarrays	Array, Hash Table, Math +2
1249	Minimum Remove to Make Valid Parentheses	Stack, String
1253	Reconstruct a 2-Row Binary Matrix	Greedy, Array, Matrix
1254	Number of Closed Islands	Depth-First Search, Breadth-First Search, Union Find +2
1261	Find Elements in a Contaminated Binary Tree	Tree, Depth-First Search, Breadth-First Search +3
1262	Greatest Sum Divisible by Three	Greedy, Array, Dynamic Programming +1
1267	Count Servers that Communicate	Depth-First Search, Breadth-First Search, Union Find +3
1268	Search Suggestions System	Trie, Array, String +3
1276	Number of Burgers with No Waste of Ingredients	Math
1277	Count Square Submatrices with All Ones	Array, Dynamic Programming, Matrix
1282	Group the People Given the Group Size They Belong To	Greedy, Array, Hash Table
1283	Find the Smallest Divisor Given a Threshold	Array, Binary Search
1286	Iterator for Combination	Design, String, Backtracking +1
1288	Remove Covered Intervals	Array, Sorting
1291	Sequential Digits	Enumeration
1292	Maximum Side Length of a Square with Sum Less than or Equal to Threshold	Array, Binary Search, Matrix +1
1296	Divide Array in Sets of K Consecutive Numbers	Greedy, Array, Hash Table +1
1297	Maximum Number of Occurrences of a Substring	Hash Table, String, Sliding Window
1300	Sum of Mutated Array Closest to Target	Array, Binary Search, Sorting
1302	Deepest Leaves Sum	Tree, Depth-First Search, Breadth-First Search +1
1305	All Elements in Two Binary Search Trees	Tree, Depth-First Search, Binary Search Tree +2
1306	Jump Game III	Depth-First Search, Breadth-First Search, Array
1310	XOR Queries of a Subarray	Bit Manipulation, Array, Prefix Sum
1311	Get Watched Videos by Your Friends	Breadth-First Search, Graph, Array +2
1314	Matrix Block Sum	Array, Matrix, Prefix Sum
1315	Sum of Nodes with Even-Valued Grandparent	Tree, Depth-First Search, Breadth-First Search +1
1318	Minimum Flips to Make a OR b Equal to c	Bit Manipulation
1319	Number of Operations to Make Network Connected	Depth-First Search, Breadth-First Search, Union Find +1
1324	Print Words Vertically	Array, String, Simulation
1325	Delete Leaves With a Given Value	Tree, Depth-First Search, Binary Tree
1328	Break a Palindrome	Greedy, String
1329	Sort the Matrix Diagonally	Array, Matrix, Sorting
1333	Filter Restaurants by Vegan-Friendly, Price and Distance	Array, Sorting
1334	Find the City With the Smallest Number of Neighbors at a Threshold Distance	Graph, Dynamic Programming, Shortest Path
1338	Reduce Array Size to The Half	Greedy, Array, Hash Table +2
1339	Maximum Product of Splitted Binary Tree	Tree, Depth-First Search, Binary Tree
1343	Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold	Array, Sliding Window
1344	Angle Between Hands of a Clock	Math
1347	Minimum Number of Steps to Make Two Strings Anagram	Hash Table, String, Counting
1348	Tweet Counts Per Frequency	Design, Hash Table, String +3
1352	Product of the Last K Numbers	Design, Array, Math +2
1353	Maximum Number of Events That Can Be Attended	Greedy, Array, Sorting +1
1357	Apply Discount Every n Orders	Design, Array, Hash Table
1358	Number of Substrings Containing All Three Characters	Hash Table, String, Sliding Window
1361	Validate Binary Tree Nodes	Tree, Depth-First Search, Breadth-First Search +3
1362	Closest Divisors	Math
1366	Rank Teams by Votes	Array, Hash Table, String +2
1367	Linked List in Binary Tree	Tree, Depth-First Search, Linked List +1
1371	Find the Longest Substring Containing Vowels in Even Counts	Bit Manipulation, Hash Table, String +1
1372	Longest ZigZag Path in a Binary Tree	Tree, Depth-First Search, Dynamic Programming +1
1375	Number of Times Binary String Is Prefix-Aligned	Array
1376	Time Needed to Inform All Employees	Tree, Depth-First Search, Breadth-First Search
1381	Design a Stack With Increment Operation	Stack, Design, Array

Problems with a complete Python solution are listed first, then by ascending problem number. Or go by technique instead: all LeetCode patterns.