Coding interview problems

3,736 problems: 937 Easy, 1,914 Medium, 885 Hard. Each runs against hidden tests, in 13 languages; database problems in SQL. Free for members.

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Problems 301–400 of 3,736

301. Keep Equal Letters Apart Hard · String, Greedy, Heap (Priority Queue), Counting
302. Toggle the Grid to Zero Hard · Array, Matrix, Bit Manipulation, Breadth-First Search
303. Stamp the Target Hard · String, Stack, Greedy, Queue
304. Partners Side by Side Hard · Array, Greedy, Union Find
305. First Day With a Gap of k Hard · Array, Sliding Window, Queue
306. Area Under Many Rectangles Hard · Array, Sorting, Math
307. Exact Tiling Check Hard · Array, Hash Table, Math
308. Does the Path Cross Itself? Hard · Array, Math
309. Reach by Adding Hard · Math
310. Cheapest Common Level Hard · Array, Sorting, Binary Search, Prefix Sum, Greedy
311. Fewest Edits to a Consecutive Run Hard · Array, Binary Search, Sliding Window, Hash Table
312. Shortest Window Reaching a Total Hard · Array, Queue, Prefix Sum, Monotonic Stack
313. Windows With Fixed Extremes Hard · Array, Sliding Window, Queue
314. Windows With Median k Hard · Array, Hash Table, Prefix Sum
315. Three Disjoint Windows Hard · Array, Dynamic Programming, Prefix Sum, Sliding Window
316. Flip k at a Time Hard · Array, Bit Manipulation, Queue, Sliding Window, Prefix Sum
317. Shortest Unique Abbreviations Hard · String, Greedy, Trie, Sorting
318. Mirror Chunk Split Hard · String, Greedy, Two Pointers
319. Prefix Match Score Sum Hard · String, Binary Search
320. Most Prefix Deletions Hard · String, Dynamic Programming
321. Smallest Subsequence With a Letter Quota Hard · String, Stack, Greedy, Monotonic Stack
322. Largest Number From Two Rows Hard · Array, Greedy, Stack, Monotonic Stack
323. Count Anagram Sentences Medium · String, Math, Counting
324. Distinct Good Binary Subsequences Hard · String, Dynamic Programming
325. Five-Digit Mirror Subsequences Hard · String, Dynamic Programming
326. Mini Lisp Evaluator Hard · String, Stack, Hash Table, Recursion
327. Brace Set Expansion Hard · String, Stack, Backtracking
328. Is It a Number? Hard · String
329. Longest Balanced Brackets Hard · String, Stack, Dynamic Programming
330. Reorder Special Bit Strings Hard · String, Recursion, Sorting
331. All Codes Sequence Hard · String, Depth-First Search, Graph
332. Best Window Around an Index Hard · Array, Two Pointers, Greedy
333. Fence Around the Trees Hard · Array, Math
334. Patch to Cover 1..n Hard · Array, Greedy
335. Same Average Split Hard · Array, Dynamic Programming, Bit Manipulation, Math
336. Triplets in Order in Both Hard · Array, Binary Search, Divide and Conquer
337. Numbers From a Digit Set Hard · Math, String, Dynamic Programming
338. Make the Grid Upper-Triangular Medium · Array, Matrix, Greedy
339. Count Ones Pyramids Hard · Array, Matrix, Dynamic Programming
340. Lamp Grid Queries Hard · Array, Hash Table
341. Puzzle Word Matches Hard · Array, String, Hash Table, Bit Manipulation, Trie
342. Cheapest and Dearest Bag Splits Hard · Array, Greedy, Sorting, Heap (Priority Queue)
343. How Often Does One Repeat Fit Another? Hard · String, Dynamic Programming
344. Most Long Mirrors Without Overlap Hard · String, Dynamic Programming, Greedy
345. Equal Circular Window Sums Hard · Array, Math, Sorting
346. Total Imbalance of Subarrays Hard · Array, Hash Table
347. Gather k Ones Together Hard · Array, Prefix Sum, Sliding Window, Greedy
348. Longest Rearrangeable Mirror Substring Hard · String, Bit Manipulation, Hash Table
349. Shortest Missing Roll Sequence Hard · Array, Greedy, Hash Table
350. Cheapest Fix for Matching Slots Hard · Array, Greedy, Hash Table, Counting
351. Longest Strictly Rising Cell Hops Hard · Array, Matrix, Sorting, Dynamic Programming
352. String From an LCP Table Hard · String, Dynamic Programming, Greedy, Matrix
353. Most Beautiful k Distinct Letters Hard · String, Hash Table, Math, Greedy
354. Split Values to Sort Hard · Array, Greedy, Math
355. Count 1-3-2-4 Patterns Hard · Array, Dynamic Programming, Prefix Sum
356. Echo Substrings Hard · String, Hash Table
357. Greatest Suffix Hard · String, Two Pointers
358. Cheapest Removal Keeping a Subsequence Hard · String, Two Pointers, Binary Search
359. Longest k-Times Subsequence Hard · String, Greedy, Backtracking
360. Split a Message With Part Tags Hard · String, Binary Search, Simulation
361. Fewest Deletions for a Divisor Hard · Array, Math, Sorting, Heap (Priority Queue)
362. Longest Battery Run Hard · Array, Binary Search, Greedy, Sorting
363. Raise Ranges to the Target Medium · Array, Greedy, Stack
364. Keep Columns Sorted Across Rows Hard · String, Array, Dynamic Programming
365. Window With a Given Hash Medium · String, Sliding Window
366. Steps to a Sorted String Hard · String, Math, Counting
367. Ransom Note Easy · Hash Table, String, Counting · Asked at Amazon, Microsoft
368. Isomorphic Strings Easy · Hash Table, String · Asked at Google, LinkedIn
369. Contains Duplicate II Easy · Array, Hash Table, Sliding Window · Asked at Amazon, Google
370. Group Anagrams Medium · Array, Hash Table, String, Sorting · Asked at Amazon, Google, Meta
371. Longest Consecutive Sequence Medium · Array, Hash Table, Union Find · Asked at Google, Amazon, Meta
372. Determine if Two Strings Are Close Medium · Hash Table, String, Sorting, Counting · Asked at Amazon
373. Substring with Concatenation of All Words Hard · Hash Table, String, Sliding Window · Asked at Amazon
374. Palindrome Pairs Hard · Array, Hash Table, String · Asked at Google, Airbnb
375. First Badge Scanned Twice Easy · Array, Hash Table
376. Pairs with Sum Divisible by K Medium · Array, Hash Table, Counting, Math
377. Four-List Zero Tuples Medium · Array, Hash Table
378. Top Played Tracks Medium · Array, Hash Table, Heap (Priority Queue), Sorting, Counting
379. Sum of Lone Sensor Readings Easy · Array, Hash Table, Counting
380. Two Gifts for an Exact Budget Easy · Array, Hash Table
381. Songs on Both Playlists Easy · Array, Hash Table, Sorting
382. Shared Stock with Repeats Easy · Array, Hash Table, Counting, Sorting
383. First Character Without a Twin Easy · String, Hash Table, Counting, Queue
384. Counting Rare Stones Easy · String, Hash Table
385. Words Typed with One Hand Easy · Array, String, Hash Table
386. Duplicated and Missing Ticket Easy · Array, Hash Table, Math
387. Sentence Uses Every Letter Easy · String, Hash Table
388. Election Winner by Votes Easy · Array, String, Hash Table, Counting
389. Value Equal to Its Count Easy · Array, Hash Table, Counting
390. All Occurrence Counts Distinct Easy · Array, Hash Table, Counting
391. Matching Pairs in a Row Easy · Array, Hash Table, Counting, Math
392. Final Stop of a Route Easy · Array, Hash Table
393. Distinct Mail Inboxes Easy · Array, String, Hash Table
394. Walker Revisits a Spot Easy · String, Hash Table, Simulation
395. Words Lonely Across Two Notes Easy · String, Hash Table, Counting, Sorting
396. Words Buildable from Tiles Easy · Array, String, Hash Table, Counting
397. Extra Letter Slipped In Easy · String, Hash Table, Counting, Bit Manipulation
398. Digit-Square Chain Reaches One Easy · Math, Hash Table
399. Best Shared Pick Easy · Array, String, Hash Table
400. Permutation of the Range Easy · Array, Hash Table