LeetCode Topics

Array

Problem Name	Difficulty
0001-two-sum	Easy
0014-longest-common-prefix	Easy
0016-3sum-closest	Medium
0026-remove-duplicates-from-sorted-array	Easy
0027-remove-element	Easy
0034-find-first-and-last-position-of-element-in-sorted-array	Medium
0049-group-anagrams	Medium
0051-n-queens	Hard
0054-spiral-matrix	Medium
0080-remove-duplicates-from-sorted-array-ii	Medium
0088-merge-sorted-array	Easy
0119-pascals-triangle-ii	Easy
0121-best-time-to-buy-and-sell-stock	Easy
0136-single-number	Easy
0189-rotate-array	Medium
0268-missing-number	Easy
0283-move-zeroes	Easy
0448-find-all-numbers-disappeared-in-an-array
0485-max-consecutive-ones
0643-maximum-average-subarray-i
0704-binary-search	Easy
0825-friends-of-appropriate-ages	Medium
0912-sort-an-array	Medium
0977-squares-of-a-sorted-array	Easy
1019-squares-of-a-sorted-array
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit	Medium
2942-find-words-containing-character	Easy
3838-weighted-word-mapping	Easy

Hash Table

Problem Name	Difficulty
0001-two-sum	Easy
0012-integer-to-roman	Medium
0013-roman-to-integer	Easy
0017-letter-combinations-of-a-phone-number	Medium
0049-group-anagrams	Medium
0141-linked-list-cycle	Easy
0160-intersection-of-two-linked-lists	Easy
0205-isomorphic-strings	Easy
0242-valid-anagram	Easy
0268-missing-number	Easy
0387-first-unique-character-in-a-string	Easy
0448-find-all-numbers-disappeared-in-an-array
0771-jewels-and-stones	Easy
3541-find-most-frequent-vowel-and-consonant	Easy

Sliding Window

Problem Name	Difficulty
0643-maximum-average-subarray-i
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit	Medium
1567-maximum-number-of-vowels-in-a-substring-of-given-length

String

Problem Name	Difficulty
0012-integer-to-roman	Medium
0013-roman-to-integer	Easy
0014-longest-common-prefix	Easy
0017-letter-combinations-of-a-phone-number	Medium
0020-valid-parentheses	Easy
0022-generate-parentheses	Medium
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy
0038-count-and-say	Medium
0049-group-anagrams	Medium
0058-length-of-last-word	Easy
0093-restore-ip-addresses	Medium
0125-valid-palindrome	Easy
0151-reverse-words-in-a-string	Medium
0205-isomorphic-strings	Easy
0242-valid-anagram	Easy
0344-reverse-string	Easy
0387-first-unique-character-in-a-string	Easy
0541-reverse-string-ii	Easy
0771-jewels-and-stones	Easy
1221-split-a-string-in-balanced-strings	Easy
1567-maximum-number-of-vowels-in-a-substring-of-given-length
1903-largest-odd-number-in-string	Easy
2942-find-words-containing-character	Easy
3541-find-most-frequent-vowel-and-consonant	Easy
3838-weighted-word-mapping	Easy

Two Pointers

Problem Name	Difficulty
0016-3sum-closest	Medium
0019-remove-nth-node-from-end-of-list	Medium
0026-remove-duplicates-from-sorted-array	Easy
0027-remove-element	Easy
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy
0061-rotate-list	Medium
0080-remove-duplicates-from-sorted-array-ii	Medium
0088-merge-sorted-array	Easy
0125-valid-palindrome	Easy
0141-linked-list-cycle	Easy
0151-reverse-words-in-a-string	Medium
0160-intersection-of-two-linked-lists	Easy
0189-rotate-array	Medium
0234-palindrome-linked-list	Easy
0283-move-zeroes	Easy
0344-reverse-string	Easy
0541-reverse-string-ii	Easy
0825-friends-of-appropriate-ages	Medium
0876-middle-of-the-linked-list	Easy
0977-squares-of-a-sorted-array	Easy
1019-squares-of-a-sorted-array

Sorting

Problem Name	Difficulty
0016-3sum-closest	Medium
0049-group-anagrams	Medium
0088-merge-sorted-array	Easy
0242-valid-anagram	Easy
0268-missing-number	Easy
0825-friends-of-appropriate-ages	Medium
0912-sort-an-array	Medium
0977-squares-of-a-sorted-array	Easy
1019-squares-of-a-sorted-array

Tree

Problem Name	Difficulty
0094-binary-tree-inorder-traversal	Easy
0100-same-tree	Easy
0101-symmetric-tree	Easy
0104-maximum-depth-of-binary-tree	Easy
3558-number-of-ways-to-assign-edge-weights-i	Medium

Depth-First Search

Problem Name	Difficulty
0094-binary-tree-inorder-traversal	Easy
0100-same-tree	Easy
0101-symmetric-tree	Easy
0104-maximum-depth-of-binary-tree	Easy
3558-number-of-ways-to-assign-edge-weights-i	Medium

Breadth-First Search

Problem Name	Difficulty
0100-same-tree	Easy
0101-symmetric-tree	Easy
0104-maximum-depth-of-binary-tree	Easy

Binary Tree

Problem Name	Difficulty
0094-binary-tree-inorder-traversal	Easy
0100-same-tree	Easy
0101-symmetric-tree	Easy
0104-maximum-depth-of-binary-tree	Easy

Matrix

Problem Name	Difficulty
0054-spiral-matrix	Medium

Simulation

Problem Name	Difficulty
0054-spiral-matrix	Medium
3838-weighted-word-mapping	Easy

Math

Problem Name	Difficulty
0002-add-two-numbers	Medium
0012-integer-to-roman	Medium
0013-roman-to-integer	Easy
0050-powx-n	Medium
0069-sqrtx	Easy
0189-rotate-array	Medium
0231-power-of-two	Easy
0268-missing-number	Easy
0343-integer-break	Medium
0509-fibonacci-number	Easy
1903-largest-odd-number-in-string	Easy
3558-number-of-ways-to-assign-edge-weights-i	Medium

Recursion

Problem Name	Difficulty
0002-add-two-numbers	Medium
0021-merge-two-sorted-lists	Easy
0024-swap-nodes-in-pairs	Medium
0050-powx-n	Medium
0203-remove-linked-list-elements	Easy
0206-reverse-linked-list	Easy
0231-power-of-two	Easy
0234-palindrome-linked-list	Easy
0509-fibonacci-number	Easy

Binary Search

Problem Name	Difficulty
0034-find-first-and-last-position-of-element-in-sorted-array	Medium
0069-sqrtx	Easy
0268-missing-number	Easy
0704-binary-search	Easy
0825-friends-of-appropriate-ages	Medium

Dynamic Programming

Problem Name	Difficulty
0022-generate-parentheses	Medium
0119-pascals-triangle-ii	Easy
0121-best-time-to-buy-and-sell-stock	Easy
0343-integer-break	Medium
0509-fibonacci-number	Easy

Trie

Problem Name	Difficulty
0014-longest-common-prefix	Easy

Backtracking

Problem Name	Difficulty
0017-letter-combinations-of-a-phone-number	Medium
0022-generate-parentheses	Medium
0051-n-queens	Hard
0093-restore-ip-addresses	Medium

Stack

Problem Name	Difficulty
0020-valid-parentheses	Easy
0094-binary-tree-inorder-traversal	Easy
0234-palindrome-linked-list	Easy

Linked List

Problem Name	Difficulty
0002-add-two-numbers	Medium
0019-remove-nth-node-from-end-of-list	Medium
0021-merge-two-sorted-lists	Easy
0024-swap-nodes-in-pairs	Medium
0061-rotate-list	Medium
0083-remove-duplicates-from-sorted-list	Easy
0141-linked-list-cycle	Easy
0160-intersection-of-two-linked-lists	Easy
0203-remove-linked-list-elements	Easy
0206-reverse-linked-list	Easy
0234-palindrome-linked-list	Easy
0328-odd-even-linked-list	Medium
0707-design-linked-list	Medium
0876-middle-of-the-linked-list	Easy

Queue

Problem Name	Difficulty
0387-first-unique-character-in-a-string	Easy
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit	Medium

Heap (Priority Queue)

Problem Name	Difficulty
0912-sort-an-array	Medium
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit	Medium

Ordered Set

Problem Name	Difficulty
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit	Medium

Monotonic Queue

Problem Name	Difficulty
1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit	Medium

Counting

Problem Name	Difficulty
0387-first-unique-character-in-a-string	Easy
1221-split-a-string-in-balanced-strings	Easy
3541-find-most-frequent-vowel-and-consonant	Easy

String Matching

Problem Name	Difficulty
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy

Bit Manipulation

Problem Name	Difficulty
0136-single-number	Easy
0231-power-of-two	Easy
0268-missing-number	Easy

Memoization

Problem Name	Difficulty
0509-fibonacci-number	Easy

Divide and Conquer

Problem Name	Difficulty
0912-sort-an-array	Medium

Merge Sort

Problem Name	Difficulty
0912-sort-an-array	Medium

Bucket Sort

Problem Name	Difficulty
0912-sort-an-array	Medium

Radix Sort

Problem Name	Difficulty
0912-sort-an-array	Medium

Counting Sort

Problem Name	Difficulty
0912-sort-an-array	Medium

Design

Problem Name	Difficulty
0707-design-linked-list	Medium

Greedy

Problem Name	Difficulty
1221-split-a-string-in-balanced-strings	Easy
1903-largest-odd-number-in-string	Easy