LeetCode Python Solutions

Welcome to my LeetCode solutions repository, where I share my solutions to various LeetCode problems using Python. This collection is organized by problem number and includes detailed explanations alongside the code.

Structure

Each problem's solution is stored in its own directory named after the problem's ID. Inside each directory, you'll find:

• Python Solution File (solution.py): This file contains the Python code implementing the solution.
• README.md: Detailed explanation of the problem, approach, and the thought process behind the solution.

Why This Repository?

• Learning Resource: Use this repository to learn different problem-solving strategies and Python coding techniques.
• Reference Guide: Easily refer back to solutions when revisiting problems or preparing for interviews.
• Collaboration: Feel free to contribute by adding more solutions or improving existing ones.

How to Use

1. Clone the Repository:

   git clone https://github.com/mohitkumhar/leetcode_solution.git
   

Contributing

Contributions are welcome! If you have a better solution, an optimization, or a new problem to add, please feel free to create a pull request.

Connect

Let's connect! Find me on LinkedIn

LeetCode Topics

Array

Problem Name	Difficulty
0001-two-sum	Easy
0004-median-of-two-sorted-arrays	Hard
0015-3sum	Medium
0018-4sum	Medium
0026-remove-duplicates-from-sorted-array	Easy
0031-next-permutation	Medium
0033-search-in-rotated-sorted-array	Medium
0034-find-first-and-last-position-of-element-in-sorted-array	Medium
0035-search-insert-position	Easy
0037-sudoku-solver	Hard
0040-combination-sum-ii	Medium
0041-first-missing-positive	Hard
0046-permutations	Medium
0047-permutations-ii	Medium
0048-rotate-image	Medium
0053-maximum-subarray	Medium
0054-spiral-matrix	Medium
0055-jump-game	Medium
0056-merge-intervals	Medium
0063-unique-paths-ii	Medium
0064-minimum-path-sum	Medium
0068-text-justification	Hard
0073-set-matrix-zeroes	Medium
0075-sort-colors	Medium
0079-word-search	Medium
0081-search-in-rotated-sorted-array-ii	Medium
0084-largest-rectangle-in-histogram	Hard
0085-maximal-rectangle	Hard
0088-merge-sorted-array	Easy
0118-pascals-triangle	Easy
0119-pascals-triangle-ii	Easy
0121-best-time-to-buy-and-sell-stock	Easy
0128-longest-consecutive-sequence	Medium
0135-candy	Hard
0136-single-number	Easy
0139-word-break	Medium
0140-word-break-ii	Hard
0152-maximum-product-subarray	Medium
0153-find-minimum-in-rotated-sorted-array	Medium
0162-find-peak-element	Medium
0169-majority-element	Easy
0174-dungeon-game	Hard
0189-rotate-array	Medium
0198-house-robber	Medium
0213-house-robber-ii	Medium
0229-majority-element-ii	Medium
0268-missing-number	Easy
0283-move-zeroes	Easy
0287-find-the-duplicate-number	Medium
0300-longest-increasing-subsequence	Medium
0368-largest-divisible-subset	Medium
0377-combination-sum-iv	Medium
0378-kth-smallest-element-in-a-sorted-matrix	Medium
0410-split-array-largest-sum	Hard
0416-partition-equal-subset-sum	Medium
0472-concatenated-words	Hard
0485-max-consecutive-ones	Easy
0486-predict-the-winner	Medium
0491-non-decreasing-subsequences	Medium
0493-reverse-pairs	Hard
0540-single-element-in-a-sorted-array	Medium
0542-01-matrix	Medium
0560-subarray-sum-equals-k	Medium
0628-maximum-product-of-three-numbers	Easy
0646-maximum-length-of-pair-chain	Medium
0679-24-game	Hard
0704-binary-search	Easy
0778-swim-in-rising-water	Hard
0839-similar-string-groups	Hard
0875-koko-eating-bananas	Medium
0877-stone-game	Medium
0931-minimum-falling-path-sum	Medium
0956-tallest-billboard	Hard
0980-unique-paths-iii	Hard
0994-rotting-oranges	Medium
1011-capacity-to-ship-packages-within-d-days	Medium
1048-longest-string-chain	Medium
1140-stone-game-ii	Medium
1219-path-with-maximum-gold	Medium
1255-maximum-score-words-formed-by-letters	Hard
1260-shift-2d-grid	Easy
1283-find-the-smallest-divisor-given-a-threshold	Medium
1288-remove-covered-intervals	Medium
1301-number-of-paths-with-max-score	Hard
1331-rank-transform-of-an-array	Easy
1386-cinema-seat-allocation	Medium
1406-stone-game-iii	Hard
1464-maximum-product-of-two-elements-in-an-array	Easy
1482-minimum-number-of-days-to-make-m-bouquets	Medium
1539-kth-missing-positive-number	Easy
1594-maximum-non-negative-product-in-a-matrix	Medium
1601-maximum-number-of-achievable-transfer-requests	Hard
1752-check-if-array-is-sorted-and-rotated	Easy
1765-map-of-highest-peak	Medium
1833-maximum-ice-cream-bars	Medium
1838-frequency-of-the-most-frequent-element	Medium
1846-maximum-element-after-decreasing-and-rearranging	Medium
1911-maximum-alternating-subsequence-sum	Medium
1926-nearest-exit-from-entrance-in-maze	Medium
1967-number-of-strings-that-appear-as-substrings-in-word	Easy
1979-find-greatest-common-divisor-of-array	Easy
2149-rearrange-array-elements-by-sign	Medium
2246-longest-path-with-different-adjacent-characters	Hard
2279-maximum-bags-with-full-capacity-of-rocks	Medium
2305-fair-distribution-of-cookies	Medium
2366-minimum-replacements-to-sort-the-array	Hard
2597-the-number-of-beautiful-subsets	Medium
2812-find-the-safest-path-in-a-grid	Medium
2958-length-of-longest-subarray-with-at-most-k-frequency	Medium
2965-find-missing-and-repeated-values	Easy
2996-smallest-missing-integer-greater-than-sequential-prefix-sum	Easy
3020-find-the-maximum-number-of-elements-in-subset	Medium
3069-distribute-elements-into-two-arrays-i	Easy
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3286-find-a-safe-walk-through-a-grid	Medium
3312-sorted-gcd-pair-queries	Hard
3336-find-the-number-of-subsequences-with-equal-gcd	Hard
3363-find-the-maximum-number-of-fruits-collected	Hard
3513-number-of-unique-xor-triplets-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium
3532-path-existence-queries-in-a-graph-i	Medium
3534-path-existence-queries-in-a-graph-ii	Hard
3620-network-recovery-pathways	Hard
3702-longest-subsequence-with-non-zero-bitwise-xor	Medium
3718-smallest-missing-multiple-of-k	Easy
3731-find-missing-elements	Easy
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard
3867-sum-of-gcd-of-formed-pairs	Medium

Breadth-First Search

Problem Name	Difficulty
0133-clone-graph	Medium
0433-minimum-genetic-mutation	Medium
0542-01-matrix	Medium
0778-swim-in-rising-water	Hard
0787-cheapest-flights-within-k-stops	Medium
0797-all-paths-from-source-to-target	Medium
0839-similar-string-groups	Hard
0841-keys-and-rooms	Medium
0886-possible-bipartition	Medium
0994-rotting-oranges	Medium
1443-minimum-time-to-collect-all-apples-in-a-tree	Medium
1466-reorder-routes-to-make-all-paths-lead-to-the-city-zero	Medium
1519-number-of-nodes-in-the-sub-tree-with-the-same-label	Medium
1765-map-of-highest-peak	Medium
1926-nearest-exit-from-entrance-in-maze	Medium
1971-find-if-path-exists-in-graph	Easy
2316-count-unreachable-pairs-of-nodes-in-an-undirected-graph	Medium
2492-minimum-score-of-a-path-between-two-cities	Medium
2812-find-the-safest-path-in-a-grid	Medium
3286-find-a-safe-walk-through-a-grid	Medium
3310-remove-methods-from-project	Medium

Matrix

Problem Name	Difficulty
0037-sudoku-solver	Hard
0048-rotate-image	Medium
0054-spiral-matrix	Medium
0063-unique-paths-ii	Medium
0064-minimum-path-sum	Medium
0073-set-matrix-zeroes	Medium
0079-word-search	Medium
0085-maximal-rectangle	Hard
0174-dungeon-game	Hard
0378-kth-smallest-element-in-a-sorted-matrix	Medium
0542-01-matrix	Medium
0778-swim-in-rising-water	Hard
0931-minimum-falling-path-sum	Medium
0980-unique-paths-iii	Hard
0994-rotting-oranges	Medium
1219-path-with-maximum-gold	Medium
1260-shift-2d-grid	Easy
1301-number-of-paths-with-max-score	Hard
1594-maximum-non-negative-product-in-a-matrix	Medium
1765-map-of-highest-peak	Medium
1926-nearest-exit-from-entrance-in-maze	Medium
2812-find-the-safest-path-in-a-grid	Medium
2965-find-missing-and-repeated-values	Easy
3286-find-a-safe-walk-through-a-grid	Medium
3363-find-the-maximum-number-of-fruits-collected	Hard

Dynamic Programming

Problem Name	Difficulty
0005-longest-palindromic-substring	Medium
0053-maximum-subarray	Medium
0055-jump-game	Medium
0062-unique-paths	Medium
0063-unique-paths-ii	Medium
0064-minimum-path-sum	Medium
0070-climbing-stairs	Easy
0072-edit-distance	Medium
0085-maximal-rectangle	Hard
0115-distinct-subsequences	Hard
0118-pascals-triangle	Easy
0119-pascals-triangle-ii	Easy
0121-best-time-to-buy-and-sell-stock	Easy
0131-palindrome-partitioning	Medium
0132-palindrome-partitioning-ii	Hard
0139-word-break	Medium
0140-word-break-ii	Hard
0152-maximum-product-subarray	Medium
0174-dungeon-game	Hard
0198-house-robber	Medium
0213-house-robber-ii	Medium
0300-longest-increasing-subsequence	Medium
0368-largest-divisible-subset	Medium
0377-combination-sum-iv	Medium
0410-split-array-largest-sum	Hard
0416-partition-equal-subset-sum	Medium
0472-concatenated-words	Hard
0486-predict-the-winner	Medium
0509-fibonacci-number	Easy
0516-longest-palindromic-subsequence	Medium
0542-01-matrix	Medium
0646-maximum-length-of-pair-chain	Medium
0647-palindromic-substrings	Medium
0787-cheapest-flights-within-k-stops	Medium
0877-stone-game	Medium
0931-minimum-falling-path-sum	Medium
0956-tallest-billboard	Hard
1048-longest-string-chain	Medium
1092-shortest-common-supersequence	Hard
1140-stone-game-ii	Medium
1143-longest-common-subsequence	Medium
1255-maximum-score-words-formed-by-letters	Hard
1301-number-of-paths-with-max-score	Hard
1312-minimum-insertion-steps-to-make-a-string-palindrome	Hard
1406-stone-game-iii	Hard
1411-number-of-ways-to-paint-n-3-grid	Hard
1420-build-array-where-you-can-find-the-maximum-exactly-k-comparisons	Hard
1510-stone-game-iv	Hard
1594-maximum-non-negative-product-in-a-matrix	Medium
1911-maximum-alternating-subsequence-sum	Medium
2305-fair-distribution-of-cookies	Medium
2597-the-number-of-beautiful-subsets	Medium
3302-find-the-lexicographically-smallest-valid-sequence	Medium
3336-find-the-number-of-subsequences-with-equal-gcd	Hard
3363-find-the-maximum-number-of-fruits-collected	Hard
3534-path-existence-queries-in-a-graph-ii	Hard
3620-network-recovery-pathways	Hard

Hash Table

Problem Name	Difficulty
0001-two-sum	Easy
0017-letter-combinations-of-a-phone-number	Medium
0037-sudoku-solver	Hard
0041-first-missing-positive	Hard
0073-set-matrix-zeroes	Medium
0128-longest-consecutive-sequence	Medium
0133-clone-graph	Medium
0139-word-break	Medium
0140-word-break-ii	Hard
0169-majority-element	Easy
0229-majority-element-ii	Medium
0268-missing-number	Easy
0352-data-stream-as-disjoint-intervals	Hard
0433-minimum-genetic-mutation	Medium
0491-non-decreasing-subsequences	Medium
0560-subarray-sum-equals-k	Medium
0839-similar-string-groups	Hard
0947-most-stones-removed-with-same-row-or-column	Medium
1048-longest-string-chain	Medium
1079-letter-tile-possibilities	Medium
1189-maximum-number-of-balloons	Easy
1255-maximum-score-words-formed-by-letters	Hard
1331-rank-transform-of-an-array	Easy
1358-number-of-substrings-containing-all-three-characters	Medium
1386-cinema-seat-allocation	Medium
1443-minimum-time-to-collect-all-apples-in-a-tree	Medium
1519-number-of-nodes-in-the-sub-tree-with-the-same-label	Medium
1593-split-a-string-into-the-max-number-of-unique-substrings	Medium
2597-the-number-of-beautiful-subsets	Medium
2958-length-of-longest-subarray-with-at-most-k-frequency	Medium
2965-find-missing-and-repeated-values	Easy
2996-smallest-missing-integer-greater-than-sequential-prefix-sum	Easy
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3020-find-the-maximum-number-of-elements-in-subset	Medium
3090-maximum-length-substring-with-two-occurrences	Easy
3312-sorted-gcd-pair-queries	Hard
3532-path-existence-queries-in-a-graph-i	Medium
3718-smallest-missing-multiple-of-k	Easy
3731-find-missing-elements	Easy
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard

String

Problem Name	Difficulty
0005-longest-palindromic-substring	Medium
0017-letter-combinations-of-a-phone-number	Medium
0068-text-justification	Hard
0072-edit-distance	Medium
0079-word-search	Medium
0115-distinct-subsequences	Hard
0125-valid-palindrome	Easy
0131-palindrome-partitioning	Medium
0132-palindrome-partitioning-ii	Hard
0139-word-break	Medium
0140-word-break-ii	Hard
0224-basic-calculator	Hard
0344-reverse-string	Easy
0433-minimum-genetic-mutation	Medium
0472-concatenated-words	Hard
0516-longest-palindromic-subsequence	Medium
0647-palindromic-substrings	Medium
0761-special-binary-string	Hard
0796-rotate-string	Easy
0839-similar-string-groups	Hard
1048-longest-string-chain	Medium
1061-lexicographically-smallest-equivalent-string	Medium
1079-letter-tile-possibilities	Medium
1081-smallest-subsequence-of-distinct-characters	Medium
1092-shortest-common-supersequence	Hard
1143-longest-common-subsequence	Medium
1189-maximum-number-of-balloons	Easy
1255-maximum-score-words-formed-by-letters	Hard
1312-minimum-insertion-steps-to-make-a-string-palindrome	Hard
1358-number-of-substrings-containing-all-three-characters	Medium
1392-longest-happy-prefix	Hard
1415-the-k-th-lexicographical-string-of-all-happy-strings-of-length-n	Medium
1593-split-a-string-into-the-max-number-of-unique-substrings	Medium
1967-number-of-strings-that-appear-as-substrings-in-word	Easy
2246-longest-path-with-different-adjacent-characters	Hard
2904-shortest-and-lexicographically-smallest-beautiful-string	Medium
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
3302-find-the-lexicographically-smallest-valid-sequence	Medium
3348-smallest-divisible-digit-product-ii	Hard
3499-maximize-active-section-with-trade-i	Medium
3517-smallest-palindromic-rearrangement-i	Medium
3756-concatenate-non-zero-digits-and-multiply-by-sum-ii	Medium

Depth-First Search

Problem Name	Difficulty
0079-word-search	Medium
0133-clone-graph	Medium
0472-concatenated-words	Hard
0778-swim-in-rising-water	Hard
0787-cheapest-flights-within-k-stops	Medium
0797-all-paths-from-source-to-target	Medium
0839-similar-string-groups	Hard
0841-keys-and-rooms	Medium
0886-possible-bipartition	Medium
0947-most-stones-removed-with-same-row-or-column	Medium
1443-minimum-time-to-collect-all-apples-in-a-tree	Medium
1466-reorder-routes-to-make-all-paths-lead-to-the-city-zero	Medium
1519-number-of-nodes-in-the-sub-tree-with-the-same-label	Medium
1971-find-if-path-exists-in-graph	Easy
2246-longest-path-with-different-adjacent-characters	Hard
2316-count-unreachable-pairs-of-nodes-in-an-undirected-graph	Medium
2359-find-closest-node-to-given-two-nodes	Medium
2492-minimum-score-of-a-path-between-two-cities	Medium
3310-remove-methods-from-project	Medium

Union-Find

Problem Name	Difficulty
0128-longest-consecutive-sequence	Medium
0352-data-stream-as-disjoint-intervals	Hard
0778-swim-in-rising-water	Hard
0839-similar-string-groups	Hard
0886-possible-bipartition	Medium
0947-most-stones-removed-with-same-row-or-column	Medium
1061-lexicographically-smallest-equivalent-string	Medium
1971-find-if-path-exists-in-graph	Easy
2316-count-unreachable-pairs-of-nodes-in-an-undirected-graph	Medium
2492-minimum-score-of-a-path-between-two-cities	Medium
2812-find-the-safest-path-in-a-grid	Medium
3532-path-existence-queries-in-a-graph-i	Medium

Graph Theory

Problem Name	Difficulty
0133-clone-graph	Medium
0787-cheapest-flights-within-k-stops	Medium
0797-all-paths-from-source-to-target	Medium
0841-keys-and-rooms	Medium
0886-possible-bipartition	Medium
0947-most-stones-removed-with-same-row-or-column	Medium
1466-reorder-routes-to-make-all-paths-lead-to-the-city-zero	Medium
1557-minimum-number-of-vertices-to-reach-all-nodes	Medium
1971-find-if-path-exists-in-graph	Easy
2246-longest-path-with-different-adjacent-characters	Hard
2316-count-unreachable-pairs-of-nodes-in-an-undirected-graph	Medium
2359-find-closest-node-to-given-two-nodes	Medium
2492-minimum-score-of-a-path-between-two-cities	Medium
3286-find-a-safe-walk-through-a-grid	Medium
3310-remove-methods-from-project	Medium
3532-path-existence-queries-in-a-graph-i	Medium
3534-path-existence-queries-in-a-graph-ii	Hard
3620-network-recovery-pathways	Hard

Counting

Problem Name	Difficulty
0169-majority-element	Easy
0229-majority-element-ii	Medium
1079-letter-tile-possibilities	Medium
1189-maximum-number-of-balloons	Easy
1255-maximum-score-words-formed-by-letters	Hard
1519-number-of-nodes-in-the-sub-tree-with-the-same-label	Medium
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3312-sorted-gcd-pair-queries	Hard
3737-count-subarrays-with-majority-element-i	Medium

Backtracking

Problem Name	Difficulty
0017-letter-combinations-of-a-phone-number	Medium
0037-sudoku-solver	Hard
0040-combination-sum-ii	Medium
0046-permutations	Medium
0047-permutations-ii	Medium
0052-n-queens-ii	Hard
0077-combinations	Medium
0079-word-search	Medium
0131-palindrome-partitioning	Medium
0140-word-break-ii	Hard
0491-non-decreasing-subsequences	Medium
0679-24-game	Hard
0797-all-paths-from-source-to-target	Medium
0980-unique-paths-iii	Hard
1079-letter-tile-possibilities	Medium
1219-path-with-maximum-gold	Medium
1255-maximum-score-words-formed-by-letters	Hard
1415-the-k-th-lexicographical-string-of-all-happy-strings-of-length-n	Medium
1593-split-a-string-into-the-max-number-of-unique-substrings	Medium
1601-maximum-number-of-achievable-transfer-requests	Hard
2305-fair-distribution-of-cookies	Medium
2597-the-number-of-beautiful-subsets	Medium
3348-smallest-divisible-digit-product-ii	Hard

Tree

Problem Name	Difficulty
1443-minimum-time-to-collect-all-apples-in-a-tree	Medium
1519-number-of-nodes-in-the-sub-tree-with-the-same-label	Medium
2246-longest-path-with-different-adjacent-characters	Hard

Topological Sort

Problem Name	Difficulty
2246-longest-path-with-different-adjacent-characters	Hard
3620-network-recovery-pathways	Hard

Heap (Priority Queue)

Problem Name	Difficulty
0378-kth-smallest-element-in-a-sorted-matrix	Medium
0778-swim-in-rising-water	Hard
0787-cheapest-flights-within-k-stops	Medium
1464-maximum-product-of-two-elements-in-an-array	Easy
2812-find-the-safest-path-in-a-grid	Medium
3286-find-a-safe-walk-through-a-grid	Medium
3620-network-recovery-pathways	Hard

Shortest Path

Problem Name	Difficulty
0787-cheapest-flights-within-k-stops	Medium
3286-find-a-safe-walk-through-a-grid	Medium
3620-network-recovery-pathways	Hard

Divide and Conquer

Problem Name	Difficulty
0004-median-of-two-sorted-arrays	Hard
0053-maximum-subarray	Medium
0169-majority-element	Easy
0493-reverse-pairs	Hard
0761-special-binary-string	Hard
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard

Segment Tree

Problem Name	Difficulty
0493-reverse-pairs	Hard
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard

Merge Sort

Problem Name	Difficulty
0493-reverse-pairs	Hard
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard

Prefix Sum

Problem Name	Difficulty
0410-split-array-largest-sum	Hard
0560-subarray-sum-equals-k	Medium
1140-stone-game-ii	Medium
1420-build-array-where-you-can-find-the-maximum-exactly-k-comparisons	Hard
1838-frequency-of-the-most-frequent-element	Medium
3312-sorted-gcd-pair-queries	Hard
3737-count-subarrays-with-majority-element-i	Medium
3739-count-subarrays-with-majority-element-ii	Hard
3756-concatenate-non-zero-digits-and-multiply-by-sum-ii	Medium

Math

Problem Name	Difficulty
0007-reverse-integer	Medium
0009-palindrome-number	Easy
0048-rotate-image	Medium
0062-unique-paths	Medium
0070-climbing-stairs	Easy
0189-rotate-array	Medium
0224-basic-calculator	Hard
0268-missing-number	Easy
0368-largest-divisible-subset	Medium
0486-predict-the-winner	Medium
0509-fibonacci-number	Easy
0628-maximum-product-of-three-numbers	Easy
0679-24-game	Hard
0877-stone-game	Medium
1140-stone-game-ii	Medium
1406-stone-game-iii	Hard
1510-stone-game-iv	Hard
1979-find-greatest-common-divisor-of-array	Easy
2366-minimum-replacements-to-sort-the-array	Hard
2597-the-number-of-beautiful-subsets	Medium
2965-find-missing-and-repeated-values	Easy
3014-minimum-number-of-pushes-to-type-word-i	Easy
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3312-sorted-gcd-pair-queries	Hard
3336-find-the-number-of-subsequences-with-equal-gcd	Hard
3345-smallest-divisible-digit-product-i	Easy
3348-smallest-divisible-digit-product-ii	Hard
3513-number-of-unique-xor-triplets-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium
3536-maximum-product-of-two-digits	Easy
3622-check-divisibility-by-digit-sum-and-product	Easy
3658-gcd-of-odd-and-even-sums	Easy
3754-concatenate-non-zero-digits-and-multiply-by-sum-i	Easy
3756-concatenate-non-zero-digits-and-multiply-by-sum-ii	Medium
3867-sum-of-gcd-of-formed-pairs	Medium

Recursion

Problem Name	Difficulty
0025-reverse-nodes-in-k-group	Hard
0203-remove-linked-list-elements	Easy
0224-basic-calculator	Hard
0486-predict-the-winner	Medium
0509-fibonacci-number	Easy

Memoization

Problem Name	Difficulty
0070-climbing-stairs	Easy
0139-word-break	Medium
0140-word-break-ii	Hard
0509-fibonacci-number	Easy

Enumeration

Problem Name	Difficulty
1291-sequential-digits	Medium
1601-maximum-number-of-achievable-transfer-requests	Hard
3020-find-the-maximum-number-of-elements-in-subset	Medium
3345-smallest-divisible-digit-product-i	Easy
3499-maximize-active-section-with-trade-i	Medium
3514-number-of-unique-xor-triplets-ii	Medium

Greedy

Problem Name	Difficulty
0055-jump-game	Medium
0135-candy	Hard
0410-split-array-largest-sum	Hard
0646-maximum-length-of-pair-chain	Medium
1081-smallest-subsequence-of-distinct-characters	Medium
1386-cinema-seat-allocation	Medium
1833-maximum-ice-cream-bars	Medium
1838-frequency-of-the-most-frequent-element	Medium
1846-maximum-element-after-decreasing-and-rearranging	Medium
2279-maximum-bags-with-full-capacity-of-rocks	Medium
2366-minimum-replacements-to-sort-the-array	Hard
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
3348-smallest-divisible-digit-product-ii	Hard
3534-path-existence-queries-in-a-graph-ii	Hard

Sorting

Problem Name	Difficulty
0015-3sum	Medium
0018-4sum	Medium
0047-permutations-ii	Medium
0056-merge-intervals	Medium
0075-sort-colors	Medium
0088-merge-sorted-array	Easy
0169-majority-element	Easy
0229-majority-element-ii	Medium
0268-missing-number	Easy
0368-largest-divisible-subset	Medium
0378-kth-smallest-element-in-a-sorted-matrix	Medium
0472-concatenated-words	Hard
0628-maximum-product-of-three-numbers	Easy
0646-maximum-length-of-pair-chain	Medium
0761-special-binary-string	Hard
1048-longest-string-chain	Medium
1288-remove-covered-intervals	Medium
1331-rank-transform-of-an-array	Easy
1464-maximum-product-of-two-elements-in-an-array	Easy
1833-maximum-ice-cream-bars	Medium
1838-frequency-of-the-most-frequent-element	Medium
1846-maximum-element-after-decreasing-and-rearranging	Medium
2279-maximum-bags-with-full-capacity-of-rocks	Medium
2597-the-number-of-beautiful-subsets	Medium
2996-smallest-missing-integer-greater-than-sequential-prefix-sum	Easy
3016-minimum-number-of-pushes-to-type-word-ii	Medium
3517-smallest-palindromic-rearrangement-i	Medium
3534-path-existence-queries-in-a-graph-ii	Hard
3536-maximum-product-of-two-digits	Easy
3731-find-missing-elements	Easy
3867-sum-of-gcd-of-formed-pairs	Medium

Sliding Window

Problem Name	Difficulty
1358-number-of-substrings-containing-all-three-characters	Medium
1838-frequency-of-the-most-frequent-element	Medium
2904-shortest-and-lexicographically-smallest-beautiful-string	Medium
2958-length-of-longest-subarray-with-at-most-k-frequency	Medium
3090-maximum-length-substring-with-two-occurrences	Easy

Counting Sort

Problem Name	Difficulty
1833-maximum-ice-cream-bars	Medium
3517-smallest-palindromic-rearrangement-i	Medium

Binary Search

Problem Name	Difficulty
0004-median-of-two-sorted-arrays	Hard
0033-search-in-rotated-sorted-array	Medium
0034-find-first-and-last-position-of-element-in-sorted-array	Medium
0035-search-insert-position	Easy
0081-search-in-rotated-sorted-array-ii	Medium
0153-find-minimum-in-rotated-sorted-array	Medium
0162-find-peak-element	Medium
0268-missing-number	Easy
0287-find-the-duplicate-number	Medium
0300-longest-increasing-subsequence	Medium
0352-data-stream-as-disjoint-intervals	Hard
0378-kth-smallest-element-in-a-sorted-matrix	Medium
0410-split-array-largest-sum	Hard
0493-reverse-pairs	Hard
0540-single-element-in-a-sorted-array	Medium
0704-binary-search	Easy
0778-swim-in-rising-water	Hard
0875-koko-eating-bananas	Medium
1011-capacity-to-ship-packages-within-d-days	Medium
1283-find-the-smallest-divisor-given-a-threshold	Medium
1482-minimum-number-of-days-to-make-m-bouquets	Medium
1539-kth-missing-positive-number	Easy
1838-frequency-of-the-most-frequent-element	Medium
2812-find-the-safest-path-in-a-grid	Medium
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3312-sorted-gcd-pair-queries	Hard
3532-path-existence-queries-in-a-graph-i	Medium
3534-path-existence-queries-in-a-graph-ii	Hard
3620-network-recovery-pathways	Hard

Two Pointers

Problem Name	Difficulty
0005-longest-palindromic-substring	Medium
0015-3sum	Medium
0018-4sum	Medium
0026-remove-duplicates-from-sorted-array	Easy
0031-next-permutation	Medium
0075-sort-colors	Medium
0088-merge-sorted-array	Easy
0125-valid-palindrome	Easy
0189-rotate-array	Medium
0283-move-zeroes	Easy
0287-find-the-duplicate-number	Medium
0344-reverse-string	Easy
0647-palindromic-substrings	Medium
1048-longest-string-chain	Medium
2149-rearrange-array-elements-by-sign	Medium
3302-find-the-lexicographically-smallest-valid-sequence	Medium
3534-path-existence-queries-in-a-graph-ii	Hard
3867-sum-of-gcd-of-formed-pairs	Medium

Bit Manipulation

Problem Name	Difficulty
0136-single-number	Easy
0268-missing-number	Easy
0287-find-the-duplicate-number	Medium
0491-non-decreasing-subsequences	Medium
0980-unique-paths-iii	Hard
1255-maximum-score-words-formed-by-letters	Hard
1386-cinema-seat-allocation	Medium
1601-maximum-number-of-achievable-transfer-requests	Hard
2305-fair-distribution-of-cookies	Medium
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
3534-path-existence-queries-in-a-graph-ii	Hard
3702-longest-subsequence-with-non-zero-bitwise-xor	Medium

Combinatorics

Problem Name	Difficulty
0062-unique-paths	Medium
2597-the-number-of-beautiful-subsets	Medium
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3312-sorted-gcd-pair-queries	Hard

Number Theory

Problem Name	Difficulty
1979-find-greatest-common-divisor-of-array	Easy
3116-kth-smallest-amount-with-single-denomination-combination	Hard
3312-sorted-gcd-pair-queries	Hard
3336-find-the-number-of-subsequences-with-equal-gcd	Hard
3348-smallest-divisible-digit-product-ii	Hard
3658-gcd-of-odd-and-even-sums	Easy
3867-sum-of-gcd-of-formed-pairs	Medium

Simulation

Problem Name	Difficulty
0054-spiral-matrix	Medium
0068-text-justification	Hard
1260-shift-2d-grid	Easy
2149-rearrange-array-elements-by-sign	Medium
3069-distribute-elements-into-two-arrays-i	Easy
3867-sum-of-gcd-of-formed-pairs	Medium

Trie

Problem Name	Difficulty
0139-word-break	Medium
0140-word-break-ii	Hard
0472-concatenated-words	Hard

Stack

Problem Name	Difficulty
0084-largest-rectangle-in-histogram	Hard
0085-maximal-rectangle	Hard
0224-basic-calculator	Hard
1081-smallest-subsequence-of-distinct-characters	Medium

Monotonic Stack

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

String Matching

Problem Name	Difficulty
0796-rotate-string	Easy
1392-longest-happy-prefix	Hard

Bitmask

Problem Name	Difficulty
1255-maximum-score-words-formed-by-letters	Hard
2305-fair-distribution-of-cookies	Medium

Rolling Hash

Problem Name	Difficulty
1392-longest-happy-prefix	Hard

Hash Function

Problem Name	Difficulty
1392-longest-happy-prefix	Hard

Game Theory

Problem Name	Difficulty
0486-predict-the-winner	Medium
0877-stone-game	Medium
1140-stone-game-ii	Medium
1406-stone-game-iii	Hard
1510-stone-game-iv	Hard

Minimax

Problem Name	Difficulty
0778-swim-in-rising-water	Hard
1140-stone-game-ii	Medium
1406-stone-game-iii	Hard
1510-stone-game-iv	Hard

Zero-Sum Game

Problem Name	Difficulty
1140-stone-game-ii	Medium
1406-stone-game-iii	Hard
1510-stone-game-iv	Hard

Quicksort

Problem Name	Difficulty
0056-merge-intervals	Medium
0075-sort-colors	Medium

Bubble Sort

Problem Name	Difficulty
0075-sort-colors	Medium

Boyer–Moore Majority Vote Algorithm

Problem Name	Difficulty
0169-majority-element	Easy
0229-majority-element-ii	Medium

Dijkstra's Algorithm

Problem Name	Difficulty
0778-swim-in-rising-water	Hard

Linked List

Problem Name	Difficulty
0025-reverse-nodes-in-k-group	Hard
0203-remove-linked-list-elements	Easy

Design

Problem Name	Difficulty
0352-data-stream-as-disjoint-intervals	Hard

Data Stream

Problem Name	Difficulty
0352-data-stream-as-disjoint-intervals	Hard

Ordered Set

Problem Name	Difficulty
0352-data-stream-as-disjoint-intervals	Hard
0493-reverse-pairs	Hard

Algorithm X

Problem Name	Difficulty
0052-n-queens-ii	Hard

Graph Coloring

Problem Name	Difficulty
1411-number-of-ways-to-paint-n-3-grid	Hard

Nim Game

Problem Name	Difficulty
1510-stone-game-iv	Hard

Sprague–Grundy Theorem

Problem Name	Difficulty
1510-stone-game-iv	Hard

Binary Indexed Tree

Problem Name	Difficulty
0493-reverse-pairs	Hard

Treap

Problem Name	Difficulty
0493-reverse-pairs	Hard

Meet in the Middle

Problem Name	Difficulty
0956-tallest-billboard	Hard

Knapsack Problem

Problem Name	Difficulty
0956-tallest-billboard	Hard

0-1 Knapsack

Problem Name	Difficulty
0956-tallest-billboard	Hard