Leetcode

Collection of LeetCode questions to ace the coding interview! - Created using LeetHub

Array

0330-patching-array
0502-ipo

Greedy

0330-patching-array
0502-ipo

Sorting

0502-ipo

Heap (Priority Queue)

0023-merge-k-sorted-lists
0502-ipo

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0024-swap-nodes-in-pairs
0061-rotate-list
0082-remove-duplicates-from-sorted-list-ii
0083-remove-duplicates-from-sorted-list

Math

0002-add-two-numbers

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs

Two Pointers

0019-remove-nth-node-from-end-of-list
0061-rotate-list
0082-remove-duplicates-from-sorted-list-ii

Divide and Conquer

0023-merge-k-sorted-lists

Merge Sort

0023-merge-k-sorted-lists

LeetCode Topics

Array

0136-single-number
0209-minimum-size-subarray-sum
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0268-missing-number
0373-find-k-pairs-with-smallest-sums
0378-kth-smallest-element-in-a-sorted-matrix
0393-utf-8-validation
0448-find-all-numbers-disappeared-in-an-array
0475-heaters
0494-target-sum
0503-next-greater-element-ii
0643-maximum-average-subarray-i
0901-advantage-shuffle
0940-fruit-into-baskets
0952-word-subsets
1025-minimum-cost-for-tickets
1063-best-sightseeing-pair
1207-delete-nodes-and-return-forest
1293-three-consecutive-odds
1333-sort-the-jumbled-numbers
1335-maximum-candies-allocated-to-k-children
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1496-lucky-numbers-in-a-matrix
1524-string-matching-in-an-array
1538-maximum-points-you-can-obtain-from-cards
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1556-make-two-arrays-equal-by-reversing-subarrays
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1711-find-valid-matrix-given-row-and-column-sums
1720-crawler-log-folder
1741-sort-array-by-increasing-frequency
1755-defuse-the-bomb
1849-maximum-absolute-sum-of-any-subarray
1876-map-of-highest-peak
1886-minimum-limit-of-balls-in-a-bag
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
1951-find-the-winner-of-the-circular-game
1972-rotating-the-box
1975-minimum-distance-to-the-target-element
1993-sum-of-all-subset-xor-totals
2022-maximum-alternating-subsequence-sum
2089-maximum-matrix-sum
2145-grid-game
2160-minimum-operations-to-make-a-uni-value-grid
2163-kth-distinct-string-in-an-array
2188-minimized-maximum-of-products-distributed-to-any-store
2232-adding-spaces-to-a-string
2262-solving-questions-with-brainpower
2265-partition-array-according-to-given-pivot
2292-counting-words-with-a-given-prefix
2306-create-binary-tree-from-descriptions
2308-divide-array-into-equal-pairs
2358-number-of-ways-to-split-array
2421-maximum-number-of-pairs-in-array
2472-build-a-matrix-with-conditions
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2476-check-distances-between-same-letters
2478-longest-nice-subarray
2502-sort-the-people
2533-bitwise-xor-of-all-pairings
2551-apply-operations-to-an-array
2552-maximum-sum-of-distinct-subarrays-with-length-k
2585-delete-greatest-value-in-each-row
2631-sort-the-students-by-their-kth-score
2665-minimum-time-to-repair-cars
2685-first-completely-painted-row-or-column
2691-count-vowel-strings-in-ranges
2707-merge-two-2d-arrays-by-summing-values
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor
2868-continuous-subarrays
2888-minimum-index-of-a-valid-split
3165-find-indices-with-index-and-value-difference-i
3170-find-indices-with-index-and-value-difference-ii
3176-minimum-sum-of-mountain-triplets-i
3186-minimum-sum-of-mountain-triplets-ii
3193-maximum-strong-pair-xor-i
3227-find-missing-and-repeated-values
3269-number-of-subarrays-that-match-a-pattern-i
3309-count-prefix-and-suffix-pairs-i
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3463-alternating-groups-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3483-alternating-groups-ii

Math

0268-missing-number
1307-ugly-number-iii
1515-find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k
1885-count-number-of-homogenous-substrings
1889-check-if-number-is-a-sum-of-powers-of-three
1951-find-the-winner-of-the-circular-game
1993-sum-of-all-subset-xor-totals
2160-minimum-operations-to-make-a-uni-value-grid
2610-closest-prime-numbers-in-range
2630-alternating-digit-sum
2649-count-total-number-of-colored-cells
2650-split-with-minimum-sum
3227-find-missing-and-repeated-values
3275-minimum-number-of-pushes-to-type-word-i

Recursion

0206-reverse-linked-list
1951-find-the-winner-of-the-circular-game

Queue

0225-implement-stack-using-queues
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1951-find-the-winner-of-the-circular-game
2868-continuous-subarrays
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Simulation

1951-find-the-winner-of-the-circular-game
2232-adding-spaces-to-a-string
2265-partition-array-according-to-given-pivot
2551-apply-operations-to-an-array
2585-delete-greatest-value-in-each-row

String

0424-longest-repeating-character-replacement
0567-permutation-in-string
0778-reorganize-string
0812-rotate-string
0952-word-subsets
1298-reverse-substrings-between-each-pair-of-parentheses
1502-construct-k-palindrome-strings
1520-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1524-string-matching-in-an-array
1537-maximum-score-after-splitting-a-string
1720-crawler-log-folder
1818-maximum-score-from-removing-substrings
1885-count-number-of-homogenous-substrings
1890-sum-of-beauty-of-all-substrings
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
2163-kth-distinct-string-in-an-array
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2221-check-if-a-parentheses-string-can-be-valid
2232-adding-spaces-to-a-string
2292-counting-words-with-a-given-prefix
2456-construct-smallest-number-from-di-string
2476-check-distances-between-same-letters
2502-sort-the-people
2691-count-vowel-strings-in-ranges
3018-make-string-a-subsequence-using-cyclic-increments
3275-minimum-number-of-pushes-to-type-word-i
3276-minimum-number-of-pushes-to-type-word-ii
3309-count-prefix-and-suffix-pairs-i
3405-count-the-number-of-special-characters-ii
3408-count-the-number-of-special-characters-i
3455-minimum-length-of-string-after-operations
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Tree

0095-unique-binary-search-trees-ii
0515-find-largest-value-in-each-tree-row
0789-kth-largest-element-in-a-stream
1207-delete-nodes-and-return-forest
1218-lowest-common-ancestor-of-deepest-leaves
1653-number-of-good-leaf-nodes-pairs
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2306-create-binary-tree-from-descriptions
2493-reverse-odd-levels-of-binary-tree
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level

Depth-First Search

0207-course-schedule
0515-find-largest-value-in-each-tree-row
1207-delete-nodes-and-return-forest
1218-lowest-common-ancestor-of-deepest-leaves
1653-number-of-good-leaf-nodes-pairs
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2493-reverse-odd-levels-of-binary-tree
2793-count-the-number-of-complete-components

Binary Tree

0095-unique-binary-search-trees-ii
0515-find-largest-value-in-each-tree-row
0789-kth-largest-element-in-a-stream
1207-delete-nodes-and-return-forest
1218-lowest-common-ancestor-of-deepest-leaves
1653-number-of-good-leaf-nodes-pairs
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2306-create-binary-tree-from-descriptions
2493-reverse-odd-levels-of-binary-tree
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level

Greedy

0778-reorganize-string
0901-advantage-shuffle
1502-construct-k-palindrome-strings
1515-find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1711-find-valid-matrix-given-row-and-column-sums
1818-maximum-score-from-removing-substrings
2089-maximum-matrix-sum
2188-minimized-maximum-of-products-distributed-to-any-store
2221-check-if-a-parentheses-string-can-be-valid
2456-construct-smallest-number-from-di-string
2509-minimize-xor
2650-split-with-minimum-sum
3275-minimum-number-of-pushes-to-type-word-i
3276-minimum-number-of-pushes-to-type-word-ii

Sorting

0215-kth-largest-element-in-an-array
0217-contains-duplicate
0268-missing-number
0378-kth-smallest-element-in-a-sorted-matrix
0475-heaters
0778-reorganize-string
0901-advantage-shuffle
1333-sort-the-jumbled-numbers
1556-make-two-arrays-equal-by-reversing-subarrays
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1741-sort-array-by-increasing-frequency
2160-minimum-operations-to-make-a-uni-value-grid
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2502-sort-the-people
2585-delete-greatest-value-in-each-row
2631-sort-the-students-by-their-kth-score
2650-split-with-minimum-sum
2888-minimum-index-of-a-valid-split
3276-minimum-number-of-pushes-to-type-word-ii

Hash Table

0217-contains-duplicate
0268-missing-number
0424-longest-repeating-character-replacement
0448-find-all-numbers-disappeared-in-an-array
0567-permutation-in-string
0778-reorganize-string
0931-maximum-frequency-stack
0940-fruit-into-baskets
0952-word-subsets
1207-delete-nodes-and-return-forest
1218-lowest-common-ancestor-of-deepest-leaves
1502-construct-k-palindrome-strings
1556-make-two-arrays-equal-by-reversing-subarrays
1741-sort-array-by-increasing-frequency
1890-sum-of-beauty-of-all-substrings
2163-kth-distinct-string-in-an-array
2306-create-binary-tree-from-descriptions
2308-divide-array-into-equal-pairs
2421-maximum-number-of-pairs-in-array
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2476-check-distances-between-same-letters
2502-sort-the-people
2552-maximum-sum-of-distinct-subarrays-with-length-k
2685-first-completely-painted-row-or-column
2707-merge-two-2d-arrays-by-summing-values
2766-find-the-prefix-common-array-of-two-arrays
2888-minimum-index-of-a-valid-split
3193-maximum-strong-pair-xor-i
3227-find-missing-and-repeated-values
3276-minimum-number-of-pushes-to-type-word-ii
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3405-count-the-number-of-special-characters-ii
3408-count-the-number-of-special-characters-i
3455-minimum-length-of-string-after-operations
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Dynamic Programming

0095-unique-binary-search-trees-ii
0494-target-sum
1025-minimum-cost-for-tickets
1063-best-sightseeing-pair
1849-maximum-absolute-sum-of-any-subarray
2022-maximum-alternating-subsequence-sum
2262-solving-questions-with-brainpower

Matrix

0378-kth-smallest-element-in-a-sorted-matrix
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1496-lucky-numbers-in-a-matrix
1711-find-valid-matrix-given-row-and-column-sums
1876-map-of-highest-peak
1972-rotating-the-box
2089-maximum-matrix-sum
2145-grid-game
2160-minimum-operations-to-make-a-uni-value-grid
2472-build-a-matrix-with-conditions
2585-delete-greatest-value-in-each-row
2631-sort-the-students-by-their-kth-score
2685-first-completely-painted-row-or-column
3227-find-missing-and-repeated-values
3335-minimum-operations-to-write-the-letter-y-on-a-grid

Graph

0207-course-schedule
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
2472-build-a-matrix-with-conditions
2793-count-the-number-of-complete-components

Topological Sort

0207-course-schedule
2472-build-a-matrix-with-conditions

Stack

0225-implement-stack-using-queues
0503-next-greater-element-ii
0931-maximum-frequency-stack
1298-reverse-substrings-between-each-pair-of-parentheses
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1720-crawler-log-folder
1818-maximum-score-from-removing-substrings
2221-check-if-a-parentheses-string-can-be-valid
2456-construct-smallest-number-from-di-string

Binary Search

0209-minimum-size-subarray-sum
0268-missing-number
0378-kth-smallest-element-in-a-sorted-matrix
0475-heaters
1307-ugly-number-iii
1335-maximum-candies-allocated-to-k-children
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1886-minimum-limit-of-balls-in-a-bag
2188-minimized-maximum-of-products-distributed-to-any-store
2665-minimum-time-to-repair-cars

Combinatorics

1307-ugly-number-iii
1993-sum-of-all-subset-xor-totals

Number Theory

1307-ugly-number-iii
2610-closest-prime-numbers-in-range

Counting

0778-reorganize-string
1502-construct-k-palindrome-strings
1890-sum-of-beauty-of-all-substrings
2163-kth-distinct-string-in-an-array
2308-divide-array-into-equal-pairs
2421-maximum-number-of-pairs-in-array
3276-minimum-number-of-pushes-to-type-word-ii
3335-minimum-operations-to-write-the-letter-y-on-a-grid
3455-minimum-length-of-string-after-operations

Two Pointers

0475-heaters
0567-permutation-in-string
0901-advantage-shuffle
1679-shortest-subarray-to-be-removed-to-make-array-sorted
1972-rotating-the-box
2232-adding-spaces-to-a-string
2265-partition-array-according-to-given-pivot
2551-apply-operations-to-an-array
2707-merge-two-2d-arrays-by-summing-values
3018-make-string-a-subsequence-using-cyclic-increments
3165-find-indices-with-index-and-value-difference-i
3170-find-indices-with-index-and-value-difference-ii

Rolling Hash

3269-number-of-subarrays-that-match-a-pattern-i
3309-count-prefix-and-suffix-pairs-i

String Matching

0812-rotate-string
1524-string-matching-in-an-array
2292-counting-words-with-a-given-prefix
3269-number-of-subarrays-that-match-a-pattern-i
3309-count-prefix-and-suffix-pairs-i

Hash Function

3269-number-of-subarrays-that-match-a-pattern-i
3309-count-prefix-and-suffix-pairs-i

Design

0225-implement-stack-using-queues
0789-kth-largest-element-in-a-stream
0931-maximum-frequency-stack
1955-seat-reservation-manager

Breadth-First Search

0207-course-schedule
0515-find-largest-value-in-each-tree-row
1218-lowest-common-ancestor-of-deepest-leaves
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1876-map-of-highest-peak
2493-reverse-odd-levels-of-binary-tree
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level
2793-count-the-number-of-complete-components

Binary Search Tree

0095-unique-binary-search-trees-ii
0789-kth-largest-element-in-a-stream

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0373-find-k-pairs-with-smallest-sums
0378-kth-smallest-element-in-a-sorted-matrix
0778-reorganize-string
0789-kth-largest-element-in-a-stream
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1955-seat-reservation-manager
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2585-delete-greatest-value-in-each-row
2868-continuous-subarrays

Data Stream

0789-kth-largest-element-in-a-stream

Database

0596-classes-more-than-5-students

Sliding Window

0209-minimum-size-subarray-sum
0424-longest-repeating-character-replacement
0567-permutation-in-string
0643-maximum-average-subarray-i
0940-fruit-into-baskets
1538-maximum-points-you-can-obtain-from-cards
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
1755-defuse-the-bomb
2478-longest-nice-subarray
2552-maximum-sum-of-distinct-subarrays-with-length-k
2868-continuous-subarrays
3193-maximum-strong-pair-xor-i
3463-alternating-groups-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3483-alternating-groups-ii
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Prefix Sum

0209-minimum-size-subarray-sum
1537-maximum-score-after-splitting-a-string
1538-maximum-points-you-can-obtain-from-cards
1895-minimum-number-of-operations-to-move-all-balls-to-each-box
2145-grid-game
2358-number-of-ways-to-split-array
2691-count-vowel-strings-in-ranges
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Ordered Set

0931-maximum-frequency-stack
1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
2868-continuous-subarrays

Monotonic Queue

1549-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit
2868-continuous-subarrays

Monotonic Stack

0503-next-greater-element-ii
1679-shortest-subarray-to-be-removed-to-make-array-sorted

Backtracking

0095-unique-binary-search-trees-ii
0494-target-sum
1993-sum-of-all-subset-xor-totals
2456-construct-smallest-number-from-di-string

Bit Manipulation

0136-single-number
0268-missing-number
0393-utf-8-validation
1520-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1993-sum-of-all-subset-xor-totals
2308-divide-array-into-equal-pairs
2478-longest-nice-subarray
2509-minimize-xor
2533-bitwise-xor-of-all-pairings
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor
3193-maximum-strong-pair-xor-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Divide and Conquer

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array

Quickselect

0215-kth-largest-element-in-an-array

Linked List

0023-merge-k-sorted-lists
0206-reverse-linked-list

Merge Sort

0023-merge-k-sorted-lists

Trie

3193-maximum-strong-pair-xor-i
3309-count-prefix-and-suffix-pairs-i

Brainteaser

2533-bitwise-xor-of-all-pairings

Shortest Path

1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid

Union Find

2793-count-the-number-of-complete-components

Enumeration

1993-sum-of-all-subset-xor-totals