Leet-Code

LeetCode Topics

Array

Problem Name	Difficulty
0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
0014-longest-common-prefix
0015-3sum
0016-3sum-closest	Medium
0018-4sum	Medium
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0037-sudoku-solver	Hard
0041-first-missing-positive	Hard
0048-rotate-image	Medium
0049-group-anagrams	Medium
0051-n-queens	Hard
0056-merge-intervals
0066-plus-one
0068-text-justification	Hard
0075-sort-colors
0078-subsets	Medium
0080-remove-duplicates-from-sorted-array-ii
0084-largest-rectangle-in-histogram	Hard
0085-maximal-rectangle	Hard
0088-merge-sorted-array
0108-convert-sorted-array-to-binary-search-tree
0118-pascals-triangle
0119-pascals-triangle-ii
0121-best-time-to-buy-and-sell-stock
0123-best-time-to-buy-and-sell-stock-iii	Hard
0135-candy	Hard
0136-single-number
0137-single-number-ii
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array	Medium
0154-find-minimum-in-rotated-sorted-array-ii	Hard
0164-maximum-gap	Medium
0169-majority-element
0179-largest-number
0189-rotate-array
0204-count-primes
0217-contains-duplicate
0219-contains-duplicate-ii	Easy
0220-contains-duplicate-iii	Hard
0228-summary-ranges	Easy
0229-majority-element-ii	Medium
0238-product-of-array-except-self	Medium
0239-sliding-window-maximum	Hard
0268-missing-number
0283-move-zeroes
0303-range-sum-query-immutable
0334-increasing-triplet-subsequence	Medium
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii	Easy
0414-third-maximum-number	Easy
0448-find-all-numbers-disappeared-in-an-array	Easy
0455-assign-cookies
0485-max-consecutive-ones	Easy
0486-predict-the-winner	Medium
0495-teemo-attacking	Easy
0540-single-element-in-a-sorted-array
0561-array-partition
0575-distribute-candies	Easy
0605-can-place-flowers	Easy
0628-maximum-product-of-three-numbers	Easy
0643-maximum-average-subarray-i	Easy
0674-longest-continuous-increasing-subsequence
0682-baseball-game
0704-binary-search
0718-maximum-length-of-repeated-subarray	Medium
0739-daily-temperatures	Medium
0832-flipping-an-image	Easy
0877-stone-game	Medium
0888-fair-candy-swap
0896-monotonic-array	Easy
0905-sort-array-by-parity
0977-squares-of-a-sorted-array	Easy
0986-interval-list-intersections	Medium
1004-max-consecutive-ones-iii	Medium
1089-duplicate-zeros	Easy
1140-stone-game-ii	Medium
1260-shift-2d-grid
1331-rank-transform-of-an-array
1351-count-negative-numbers-in-a-sorted-matrix
1365-how-many-numbers-are-smaller-than-the-current-number	Easy
1390-four-divisors	Medium
1406-stone-game-iii	Hard
1431-kids-with-the-greatest-number-of-candies	Easy
1464-maximum-product-of-two-elements-in-an-array	Easy
1493-longest-subarray-of-1s-after-deleting-one-element	Medium
1497-check-if-array-pairs-are-divisible-by-k	Medium
1512-number-of-good-pairs
1550-three-consecutive-odds	Easy
1563-stone-game-v	Hard
1598-crawler-log-folder
1652-defuse-the-bomb	Easy
1672-richest-customer-wealth	Easy
1679-max-number-of-k-sum-pairs	Medium
1752-check-if-array-is-sorted-and-rotated
1822-sign-of-the-product-of-an-array	Easy
1833-maximum-ice-cream-bars
1846-maximum-element-after-decreasing-and-rearranging
1886-determine-whether-matrix-can-be-obtained-by-rotation	Easy
1967-number-of-strings-that-appear-as-substrings-in-word
1979-find-greatest-common-divisor-of-array
2029-stone-game-ix	Medium
2053-kth-distinct-string-in-an-array	Easy
2089-find-target-indices-after-sorting-array	Easy
2094-finding-3-digit-even-numbers
2114-maximum-number-of-words-found-in-sentences
2144-minimum-cost-of-buying-candies-with-discount
2213-longest-substring-of-one-repeating-character	Hard
2215-find-the-difference-of-two-arrays	Easy
2248-intersection-of-multiple-arrays	Easy
2441-largest-positive-integer-that-exists-with-its-negative	Easy
2535-difference-between-element-sum-and-digit-sum-of-an-array	Easy
2798-number-of-employees-who-met-the-target	Easy
2942-find-words-containing-character	Easy
2958-length-of-longest-subarray-with-at-most-k-frequency	Medium
2974-minimum-number-game	Easy
3024-type-of-triangle	Easy
3069-distribute-elements-into-two-arrays-i	Easy
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3232-find-if-digit-game-can-be-won	Easy
3379-transformed-array
3427-sum-of-variable-length-subarrays
3471-find-the-largest-almost-missing-integer	Easy
3483-unique-3-digit-even-numbers
3501-maximize-active-section-with-trade-ii	Hard
3513-number-of-unique-xor-triplets-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium
3702-longest-subsequence-with-non-zero-bitwise-xor	Medium
3731-find-missing-elements	Easy
3867-sum-of-gcd-of-formed-pairs
3912-valid-elements-in-an-array
3969-valid-subarrays-with-matching-sum-digits-i

String

Problem Name	Difficulty
0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0006-zigzag-conversion	Medium
0008-string-to-integer-atoi
0010-regular-expression-matching	Hard
0012-integer-to-roman
0013-roman-to-integer
0014-longest-common-prefix
0020-valid-parentheses
0022-generate-parentheses	Medium
0028-find-the-index-of-the-first-occurrence-in-a-string
0030-substring-with-concatenation-of-all-words	Hard
0043-multiply-strings	Medium
0044-wildcard-matching	Hard
0049-group-anagrams	Medium
0058-length-of-last-word
0067-add-binary
0068-text-justification	Hard
0076-minimum-window-substring	Hard
0115-distinct-subsequences	Hard
0125-valid-palindrome	Easy
0151-reverse-words-in-a-string	Medium
0179-largest-number
0224-basic-calculator
0242-valid-anagram
0290-word-pattern	Easy
0344-reverse-string	Easy
0345-reverse-vowels-of-a-string	Easy
0387-first-unique-character-in-a-string	Easy
0392-is-subsequence	Easy
0412-fizz-buzz	Easy
0443-string-compression	Medium
0504-base-7	Easy
0541-reverse-string-ii	Easy
0551-student-attendance-record-i
0657-robot-return-to-origin	Easy
0680-valid-palindrome-ii	Easy
0709-to-lower-case	Easy
0844-backspace-string-compare
0925-long-pressed-name	Easy
1071-greatest-common-divisor-of-strings	Easy
1081-smallest-subsequence-of-distinct-characters
1147-longest-chunked-palindrome-decomposition	Hard
1189-maximum-number-of-balloons
1358-number-of-substrings-containing-all-three-characters
1598-crawler-log-folder
1768-merge-strings-alternately	Easy
1832-check-if-the-sentence-is-pangram	Easy
1927-sum-game	Medium
1967-number-of-strings-that-appear-as-substrings-in-word
2042-check-if-numbers-are-ascending-in-a-sentence
2053-kth-distinct-string-in-an-array	Easy
2114-maximum-number-of-words-found-in-sentences
2213-longest-substring-of-one-repeating-character	Hard
2390-removing-stars-from-a-string
2942-find-words-containing-character	Easy
3014-minimum-number-of-pushes-to-type-word-i	Easy
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3090-maximum-length-substring-with-two-occurrences	Easy
3110-score-of-a-string	Easy
3302-find-the-lexicographically-smallest-valid-sequence	Medium
3499-maximize-active-section-with-trade-i
3501-maximize-active-section-with-trade-ii	Hard
3517-smallest-palindromic-rearrangement-i	Medium
3518-smallest-palindromic-rearrangement-ii	Hard
3968-maximum-manhattan-distance-after-all-moves
3970-shortest-path-with-at-most-k-consecutive-identical-characters

Hash Table

Problem Name	Difficulty
0001-two-sum
0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0013-roman-to-integer
0030-substring-with-concatenation-of-all-words	Hard
0037-sudoku-solver	Hard
0041-first-missing-positive	Hard
0049-group-anagrams	Medium
0076-minimum-window-substring	Hard
0141-linked-list-cycle
0160-intersection-of-two-linked-lists
0169-majority-element
0202-happy-number
0217-contains-duplicate
0219-contains-duplicate-ii	Easy
0229-majority-element-ii	Medium
0242-valid-anagram
0268-missing-number
0290-word-pattern	Easy
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii	Easy
0387-first-unique-character-in-a-string	Easy
0448-find-all-numbers-disappeared-in-an-array	Easy
0575-distribute-candies	Easy
0888-fair-candy-swap
1189-maximum-number-of-balloons
1331-rank-transform-of-an-array
1358-number-of-substrings-containing-all-three-characters
1365-how-many-numbers-are-smaller-than-the-current-number	Easy
1497-check-if-array-pairs-are-divisible-by-k	Medium
1512-number-of-good-pairs
1679-max-number-of-k-sum-pairs	Medium
1832-check-if-the-sentence-is-pangram	Easy
2053-kth-distinct-string-in-an-array	Easy
2094-finding-3-digit-even-numbers
2215-find-the-difference-of-two-arrays	Easy
2248-intersection-of-multiple-arrays	Easy
2441-largest-positive-integer-that-exists-with-its-negative	Easy
2958-length-of-longest-subarray-with-at-most-k-frequency	Medium
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3090-maximum-length-substring-with-two-occurrences	Easy
3471-find-the-largest-almost-missing-integer	Easy
3483-unique-3-digit-even-numbers
3518-smallest-palindromic-rearrangement-ii	Hard
3731-find-missing-elements	Easy
3969-valid-subarrays-with-matching-sum-digits-i

Linked List

Problem Name	Difficulty
0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists	Hard
0024-swap-nodes-in-pairs	Medium
0083-remove-duplicates-from-sorted-list
0141-linked-list-cycle
0160-intersection-of-two-linked-lists

Math

Problem Name	Difficulty
0002-add-two-numbers
0007-reverse-integer
0009-palindrome-number	Easy
0012-integer-to-roman
0013-roman-to-integer
0029-divide-two-integers	Medium
0043-multiply-strings	Medium
0048-rotate-image	Medium
0050-powx-n	Medium
0060-permutation-sequence	Hard
0066-plus-one
0067-add-binary
0069-sqrtx
0070-climbing-stairs
0172-factorial-trailing-zeroes
0189-rotate-array
0202-happy-number
0204-count-primes
0224-basic-calculator
0258-add-digits	Easy
0268-missing-number
0292-nim-game
0319-bulb-switcher
0342-power-of-four	Easy
0412-fizz-buzz	Easy
0486-predict-the-winner	Medium
0492-construct-the-rectangle	Easy
0504-base-7	Easy
0507-perfect-number	Easy
0628-maximum-product-of-three-numbers	Easy
0633-sum-of-square-numbers
0877-stone-game	Medium
1071-greatest-common-divisor-of-strings	Easy
1140-stone-game-ii	Medium
1281-subtract-the-product-and-sum-of-digits-of-an-integer	Easy
1323-maximum-69-number
1342-number-of-steps-to-reduce-a-number-to-zero
1390-four-divisors	Medium
1406-stone-game-iii	Hard
1486-xor-operation-in-an-array	Easy
1512-number-of-good-pairs
1563-stone-game-v	Hard
1822-sign-of-the-product-of-an-array	Easy
1927-sum-game	Medium
1979-find-greatest-common-divisor-of-array
2029-stone-game-ix	Medium
2396-strictly-palindromic-number
2520-count-the-digits-that-divide-a-number	Easy
2535-difference-between-element-sum-and-digit-sum-of-an-array	Easy
2652-sum-multiples	Easy
2769-find-the-maximum-achievable-number	Easy
2894-divisible-and-non-divisible-sums-difference	Easy
2928-distribute-candies-among-children-i	Easy
3014-minimum-number-of-pushes-to-type-word-i	Easy
3024-type-of-triangle	Easy
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3232-find-if-digit-game-can-be-won	Easy
3270-find-the-key-of-the-numbers
3345-smallest-divisible-digit-product-i	Easy
3513-number-of-unique-xor-triplets-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium
3518-smallest-palindromic-rearrangement-ii	Hard
3536-maximum-product-of-two-digits	Easy
3622-check-divisibility-by-digit-sum-and-product	Easy
3658-gcd-of-odd-and-even-sums
3754-concatenate-non-zero-digits-and-multiply-by-sum-i
3867-sum-of-gcd-of-formed-pairs
3968-maximum-manhattan-distance-after-all-moves

Recursion

Problem Name	Difficulty
0002-add-two-numbers
0010-regular-expression-matching	Hard
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs	Medium
0044-wildcard-matching	Hard
0050-powx-n	Medium
0060-permutation-sequence	Hard
0224-basic-calculator
0342-power-of-four	Easy
0486-predict-the-winner	Medium
2094-finding-3-digit-even-numbers
3483-unique-3-digit-even-numbers

Sliding Window

Problem Name	Difficulty
0003-longest-substring-without-repeating-characters
0030-substring-with-concatenation-of-all-words	Hard
0076-minimum-window-substring	Hard
0219-contains-duplicate-ii	Easy
0220-contains-duplicate-iii	Hard
0239-sliding-window-maximum	Hard
0643-maximum-average-subarray-i	Easy
0718-maximum-length-of-repeated-subarray	Medium
1004-max-consecutive-ones-iii	Medium
1358-number-of-substrings-containing-all-three-characters
1493-longest-subarray-of-1s-after-deleting-one-element	Medium
1652-defuse-the-bomb	Easy
2958-length-of-longest-subarray-with-at-most-k-frequency	Medium
3090-maximum-length-substring-with-two-occurrences	Easy
3969-valid-subarrays-with-matching-sum-digits-i

Two Pointers

Problem Name	Difficulty
0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0016-3sum-closest	Medium
0018-4sum	Medium
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0031-next-permutation
0075-sort-colors
0080-remove-duplicates-from-sorted-array-ii
0088-merge-sorted-array
0125-valid-palindrome	Easy
0141-linked-list-cycle
0151-reverse-words-in-a-string	Medium
0160-intersection-of-two-linked-lists
0189-rotate-array
0202-happy-number
0283-move-zeroes
0344-reverse-string	Easy
0345-reverse-vowels-of-a-string	Easy
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii	Easy
0392-is-subsequence	Easy
0443-string-compression	Medium
0455-assign-cookies
0541-reverse-string-ii	Easy
0633-sum-of-square-numbers
0680-valid-palindrome-ii	Easy
0832-flipping-an-image	Easy
0844-backspace-string-compare
0905-sort-array-by-parity
0925-long-pressed-name	Easy
0977-squares-of-a-sorted-array	Easy
0986-interval-list-intersections	Medium
1089-duplicate-zeros	Easy
1147-longest-chunked-palindrome-decomposition	Hard
1679-max-number-of-k-sum-pairs	Medium
1768-merge-strings-alternately	Easy
2396-strictly-palindromic-number
2441-largest-positive-integer-that-exists-with-its-negative	Easy
3302-find-the-lexicographically-smallest-valid-sequence	Medium
3867-sum-of-gcd-of-formed-pairs

Binary Search

Problem Name	Difficulty
0004-median-of-two-sorted-arrays
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0069-sqrtx
0153-find-minimum-in-rotated-sorted-array	Medium
0154-find-minimum-in-rotated-sorted-array-ii	Hard
0268-missing-number
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii	Easy
0540-single-element-in-a-sorted-array
0633-sum-of-square-numbers
0704-binary-search
0718-maximum-length-of-repeated-subarray	Medium
0888-fair-candy-swap
1004-max-consecutive-ones-iii	Medium
1351-count-negative-numbers-in-a-sorted-matrix
2089-find-target-indices-after-sorting-array	Easy
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3501-maximize-active-section-with-trade-ii	Hard

Sorting

Problem Name	Difficulty
0015-3sum
0016-3sum-closest	Medium
0018-4sum	Medium
0049-group-anagrams	Medium
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0164-maximum-gap	Medium
0169-majority-element
0179-largest-number
0217-contains-duplicate
0220-contains-duplicate-iii	Hard
0229-majority-element-ii	Medium
0242-valid-anagram
0268-missing-number
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii	Easy
0414-third-maximum-number	Easy
0455-assign-cookies
0561-array-partition
0628-maximum-product-of-three-numbers	Easy
0888-fair-candy-swap
0905-sort-array-by-parity
0977-squares-of-a-sorted-array	Easy
1331-rank-transform-of-an-array
1365-how-many-numbers-are-smaller-than-the-current-number	Easy
1464-maximum-product-of-two-elements-in-an-array	Easy
1679-max-number-of-k-sum-pairs	Medium
1833-maximum-ice-cream-bars
1846-maximum-element-after-decreasing-and-rearranging
2089-find-target-indices-after-sorting-array	Easy
2094-finding-3-digit-even-numbers
2144-minimum-cost-of-buying-candies-with-discount
2248-intersection-of-multiple-arrays	Easy
2441-largest-positive-integer-that-exists-with-its-negative	Easy
2974-minimum-number-game	Easy
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3024-type-of-triangle	Easy
3517-smallest-palindromic-rearrangement-i	Medium
3536-maximum-product-of-two-digits	Easy
3731-find-missing-elements	Easy
3867-sum-of-gcd-of-formed-pairs

Trie

Problem Name	Difficulty
0014-longest-common-prefix

Divide and Conquer

Problem Name	Difficulty
0004-median-of-two-sorted-arrays
0023-merge-k-sorted-lists	Hard
0108-convert-sorted-array-to-binary-search-tree
0169-majority-element
0190-reverse-bits

Counting

Problem Name	Difficulty
0169-majority-element
0229-majority-element-ii	Medium
0387-first-unique-character-in-a-string	Easy
1189-maximum-number-of-balloons
1497-check-if-array-pairs-are-divisible-by-k	Medium
1512-number-of-good-pairs
2029-stone-game-ix	Medium
2053-kth-distinct-string-in-an-array	Easy
2248-intersection-of-multiple-arrays	Easy
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3518-smallest-palindromic-rearrangement-ii	Hard
3968-maximum-manhattan-distance-after-all-moves

Bit Manipulation

Problem Name	Difficulty
0029-divide-two-integers	Medium
0067-add-binary
0078-subsets	Medium
0136-single-number
0137-single-number-ii
0190-reverse-bits
0268-missing-number
0338-counting-bits	Easy
0342-power-of-four	Easy
0832-flipping-an-image	Easy
1318-minimum-flips-to-make-a-or-b-equal-to-c	Medium
1342-number-of-steps-to-reduce-a-number-to-zero
1486-xor-operation-in-an-array	Easy
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3513-number-of-unique-xor-triplets-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium
3702-longest-subsequence-with-non-zero-bitwise-xor	Medium

Dynamic Programming

Problem Name	Difficulty
0005-longest-palindromic-substring
0010-regular-expression-matching	Hard
0022-generate-parentheses	Medium
0044-wildcard-matching	Hard
0070-climbing-stairs
0085-maximal-rectangle	Hard
0115-distinct-subsequences	Hard
0118-pascals-triangle
0119-pascals-triangle-ii
0121-best-time-to-buy-and-sell-stock
0123-best-time-to-buy-and-sell-stock-iii	Hard
0152-maximum-product-subarray
0338-counting-bits	Easy
0392-is-subsequence	Easy
0486-predict-the-winner	Medium
0718-maximum-length-of-repeated-subarray	Medium
0790-domino-and-tromino-tiling	Medium
0877-stone-game	Medium
1140-stone-game-ii	Medium
1147-longest-chunked-palindrome-decomposition	Hard
1406-stone-game-iii	Hard
1493-longest-subarray-of-1s-after-deleting-one-element	Medium
1563-stone-game-v	Hard
3302-find-the-lexicographically-smallest-valid-sequence	Medium

Stack

Problem Name	Difficulty
0020-valid-parentheses
0084-largest-rectangle-in-histogram	Hard
0085-maximal-rectangle	Hard
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0224-basic-calculator
0589-n-ary-tree-preorder-traversal
0682-baseball-game
0739-daily-temperatures	Medium
0844-backspace-string-compare
1081-smallest-subsequence-of-distinct-characters
1598-crawler-log-folder
2390-removing-stars-from-a-string

Greedy

Problem Name	Difficulty
0011-container-with-most-water
0044-wildcard-matching	Hard
0135-candy	Hard
0179-largest-number
0334-increasing-triplet-subsequence	Medium
0455-assign-cookies
0561-array-partition
0605-can-place-flowers	Easy
0680-valid-palindrome-ii	Easy
1081-smallest-subsequence-of-distinct-characters
1147-longest-chunked-palindrome-decomposition	Hard
1323-maximum-69-number
1833-maximum-ice-cream-bars
1846-maximum-element-after-decreasing-and-rearranging
1927-sum-game	Medium
2029-stone-game-ix	Medium
2144-minimum-cost-of-buying-candies-with-discount
3014-minimum-number-of-pushes-to-type-word-i	Easy
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3302-find-the-lexicographically-smallest-valid-sequence	Medium

Counting Sort

Problem Name	Difficulty
0561-array-partition
1365-how-many-numbers-are-smaller-than-the-current-number	Easy
1833-maximum-ice-cream-bars
3517-smallest-palindromic-rearrangement-i	Medium

Enumeration

Problem Name	Difficulty
0204-count-primes
1291-sequential-digits
2094-finding-3-digit-even-numbers
2928-distribute-candies-among-children-i	Easy
3345-smallest-divisible-digit-product-i	Easy
3483-unique-3-digit-even-numbers
3499-maximize-active-section-with-trade-i
3514-number-of-unique-xor-triplets-ii	Medium
3969-valid-subarrays-with-matching-sum-digits-i

Prefix Sum

Problem Name	Difficulty
0238-product-of-array-except-self	Medium
0303-range-sum-query-immutable
1004-max-consecutive-ones-iii	Medium
1140-stone-game-ii	Medium
3427-sum-of-variable-length-subarrays
3969-valid-subarrays-with-matching-sum-digits-i

Graph Theory

Problem Name	Difficulty
2492-minimum-score-of-a-path-between-two-cities
2685-count-the-number-of-complete-components
3970-shortest-path-with-at-most-k-consecutive-identical-characters

Heap (Priority Queue)

Problem Name	Difficulty
0023-merge-k-sorted-lists	Hard
0239-sliding-window-maximum	Hard
1464-maximum-product-of-two-elements-in-an-array	Easy
2974-minimum-number-game	Easy
3970-shortest-path-with-at-most-k-consecutive-identical-characters

Shortest Path

Problem Name	Difficulty
3970-shortest-path-with-at-most-k-consecutive-identical-characters

Depth-First Search

Problem Name	Difficulty
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0589-n-ary-tree-preorder-traversal
2492-minimum-score-of-a-path-between-two-cities
2685-count-the-number-of-complete-components

Breadth-First Search

Problem Name	Difficulty
2492-minimum-score-of-a-path-between-two-cities
2685-count-the-number-of-complete-components

Union-Find

Problem Name	Difficulty
2492-minimum-score-of-a-path-between-two-cities
2685-count-the-number-of-complete-components

String Matching

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

Simulation

Problem Name	Difficulty
0043-multiply-strings	Medium
0067-add-binary
0068-text-justification	Hard
0258-add-digits	Easy
0412-fizz-buzz	Easy
0495-teemo-attacking	Easy
0657-robot-return-to-origin	Easy
0682-baseball-game
0832-flipping-an-image	Easy
0844-backspace-string-compare
1260-shift-2d-grid
2390-removing-stars-from-a-string
2974-minimum-number-game	Easy
3069-distribute-elements-into-two-arrays-i	Easy
3379-transformed-array
3867-sum-of-gcd-of-formed-pairs

Tree

Problem Name	Difficulty
0094-binary-tree-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0144-binary-tree-preorder-traversal
0589-n-ary-tree-preorder-traversal

Binary Tree

Problem Name	Difficulty
0094-binary-tree-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0144-binary-tree-preorder-traversal

Number Theory

Problem Name	Difficulty
0204-count-primes
0258-add-digits	Easy
1979-find-greatest-common-divisor-of-array
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3658-gcd-of-odd-and-even-sums
3867-sum-of-gcd-of-formed-pairs

Design

Problem Name	Difficulty
0303-range-sum-query-immutable

Memoization

Problem Name	Difficulty
0070-climbing-stairs

Brainteaser

Problem Name	Difficulty
0292-nim-game
0319-bulb-switcher
2396-strictly-palindromic-number

Game Theory

Problem Name	Difficulty
0292-nim-game
0486-predict-the-winner	Medium
0877-stone-game	Medium
1140-stone-game-ii	Medium
1406-stone-game-iii	Hard
1563-stone-game-v	Hard
1927-sum-game	Medium
2029-stone-game-ix	Medium

Matrix

Problem Name	Difficulty
0037-sudoku-solver	Hard
0048-rotate-image	Medium
0085-maximal-rectangle	Hard
0832-flipping-an-image	Easy
1260-shift-2d-grid
1351-count-negative-numbers-in-a-sorted-matrix
1672-richest-customer-wealth	Easy
1886-determine-whether-matrix-can-be-obtained-by-rotation	Easy

Monotonic Stack

Problem Name	Difficulty
0084-largest-rectangle-in-histogram	Hard
0085-maximal-rectangle	Hard
0739-daily-temperatures	Medium
1081-smallest-subsequence-of-distinct-characters

Binary Search Tree

Problem Name	Difficulty
0108-convert-sorted-array-to-binary-search-tree

Bucket Sort

Problem Name	Difficulty
0164-maximum-gap	Medium
0220-contains-duplicate-iii	Hard

Ordered Set

Problem Name	Difficulty
0220-contains-duplicate-iii	Hard
2213-longest-substring-of-one-repeating-character	Hard

Segment Tree

Problem Name	Difficulty
2213-longest-substring-of-one-repeating-character	Hard
3501-maximize-active-section-with-trade-ii	Hard

Combinatorics

Problem Name	Difficulty
2928-distribute-candies-among-children-i	Easy
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3518-smallest-palindromic-rearrangement-ii	Hard

Rolling Hash

Problem Name	Difficulty
0718-maximum-length-of-repeated-subarray	Medium
1147-longest-chunked-palindrome-decomposition	Hard

Hash Function

Problem Name	Difficulty
0718-maximum-length-of-repeated-subarray	Medium
1147-longest-chunked-palindrome-decomposition	Hard

Queue

Problem Name	Difficulty
0239-sliding-window-maximum	Hard
0387-first-unique-character-in-a-string	Easy

Monotonic Queue

Problem Name	Difficulty
0239-sliding-window-maximum	Hard

Range Minimum/Maximum Query

Problem Name	Difficulty
0084-largest-rectangle-in-histogram	Hard
0239-sliding-window-maximum	Hard

Merge Sort

Problem Name	Difficulty
0023-merge-k-sorted-lists	Hard

Tournament Sort

Problem Name	Difficulty
0023-merge-k-sorted-lists	Hard

Backtracking

Problem Name	Difficulty
0022-generate-parentheses	Medium
0037-sudoku-solver	Hard
0051-n-queens	Hard
0052-n-queens-ii	Hard
0078-subsets	Medium

Minimax

Problem Name	Difficulty
1140-stone-game-ii	Medium
2029-stone-game-ix	Medium

Zero-Sum Game

Problem Name	Difficulty
1140-stone-game-ii	Medium
2029-stone-game-ix	Medium

Algorithm X

Problem Name	Difficulty
0037-sudoku-solver	Hard
0051-n-queens	Hard
0052-n-queens-ii	Hard

Radix Sort

Problem Name	Difficulty
0164-maximum-gap	Medium

Pigeonhole Principle

Problem Name	Difficulty
0164-maximum-gap	Medium

Nim Game

Problem Name	Difficulty
2029-stone-game-ix	Medium

Dancing Links

Problem Name	Difficulty
0037-sudoku-solver	Hard

Bracket Sequences

Problem Name	Difficulty
0022-generate-parentheses	Medium

Sweep Line

Problem Name	Difficulty
0986-interval-list-intersections	Medium