LeetCode Topics

Database

Problem Name	Difficulty
0614-second-degree-follower	Medium
1107-new-users-daily-count	Medium
1142-user-activity-for-the-past-30-days-ii	Easy
1149-article-views-ii	Medium
1205-monthly-transactions-ii	Medium
1212-team-scores-in-football-tournament	Medium
1241-number-of-comments-per-post	Easy
1264-page-recommendations	Medium
1285-find-the-start-and-end-number-of-continuous-ranges	Medium
1350-students-with-invalid-departments	Easy
1355-activity-participants	Medium
1435-create-a-session-bar-chart	Easy
1440-evaluate-boolean-expression	Medium
1445-apples-oranges	Medium
1532-the-most-recent-three-orders	Medium
1607-sellers-with-no-sales	Easy
1623-all-valid-triplets-that-can-represent-a-country	Easy
1699-number-of-calls-between-two-persons	Medium
1811-find-interview-candidates	Medium
1821-find-customers-with-positive-revenue-this-year	Easy
1831-maximum-transaction-each-day	Medium
1843-suspicious-bank-accounts	Medium

String

Problem Name	Difficulty
0010-regular-expression-matching	Hard
0017-letter-combinations-of-a-phone-number	Medium
0049-group-anagrams	Medium
0420-strong-password-checker	Hard
0459-repeated-substring-pattern	Easy
0767-reorganize-string	Medium

String Matching

Problem Name	Difficulty
0459-repeated-substring-pattern	Easy

Array

Problem Name	Difficulty
0004-median-of-two-sorted-arrays	Hard
0049-group-anagrams	Medium
0163-missing-ranges	Easy
0349-intersection-of-two-arrays	Easy
0407-trapping-rain-water-ii	Hard
0410-split-array-largest-sum	Hard
1929-concatenation-of-array	Easy

Hash Table

Problem Name	Difficulty
0017-letter-combinations-of-a-phone-number	Medium
0049-group-anagrams	Medium
0349-intersection-of-two-arrays	Easy
0767-reorganize-string	Medium

Two Pointers

Problem Name	Difficulty
0349-intersection-of-two-arrays	Easy

Binary Search

Problem Name	Difficulty
0004-median-of-two-sorted-arrays	Hard
0349-intersection-of-two-arrays	Easy
0410-split-array-largest-sum	Hard

Sorting

Problem Name	Difficulty
0049-group-anagrams	Medium
0349-intersection-of-two-arrays	Easy
0767-reorganize-string	Medium

Linked List

Problem Name	Difficulty
0025-reverse-nodes-in-k-group	Hard

Recursion

Problem Name	Difficulty
0010-regular-expression-matching	Hard
0025-reverse-nodes-in-k-group	Hard

Breadth-First Search

Problem Name	Difficulty
0407-trapping-rain-water-ii	Hard

Heap (Priority Queue)

Problem Name	Difficulty
0407-trapping-rain-water-ii	Hard
0420-strong-password-checker	Hard
0767-reorganize-string	Medium

Matrix

Problem Name	Difficulty
0407-trapping-rain-water-ii	Hard

Dynamic Programming

Problem Name	Difficulty
0010-regular-expression-matching	Hard
0410-split-array-largest-sum	Hard

Greedy

Problem Name	Difficulty
0410-split-array-largest-sum	Hard
0420-strong-password-checker	Hard
0767-reorganize-string	Medium

Prefix Sum

Problem Name	Difficulty
0410-split-array-largest-sum	Hard

Divide and Conquer

Problem Name	Difficulty
0004-median-of-two-sorted-arrays	Hard

Simulation

Problem Name	Difficulty
1929-concatenation-of-array	Easy

Counting

Problem Name	Difficulty
0767-reorganize-string	Medium

Backtracking

Problem Name	Difficulty
0017-letter-combinations-of-a-phone-number	Medium