LeetCode

Collection of LeetCode questions to ace the coding interview! - Created using LeetHub v2

Array

0074-search-a-2d-matrix
0982-minimum-increment-to-make-array-unique
1039-find-the-town-judge
2388-replace-elements-in-an-array

Greedy

0982-minimum-increment-to-make-array-unique

Sorting

0982-minimum-increment-to-make-array-unique

Counting

0982-minimum-increment-to-make-array-unique

Binary Search

0074-search-a-2d-matrix

Matrix

0074-search-a-2d-matrix

Graph

1039-find-the-town-judge
1916-find-center-of-star-graph

Hash Table

1039-find-the-town-judge
2388-replace-elements-in-an-array

Simulation

2388-replace-elements-in-an-array

LeetCode Topics

Array

0015-3sum
0039-combination-sum
0040-combination-sum-ii
0048-rotate-image
0064-minimum-path-sum
0075-sort-colors
0120-triangle
0152-maximum-product-subarray
0167-two-sum-ii-input-array-is-sorted
0179-largest-number
0189-rotate-array
0215-kth-largest-element-in-an-array
0219-contains-duplicate-ii
0300-longest-increasing-subsequence
0322-coin-change
0350-intersection-of-two-arrays-ii
0407-trapping-rain-water-ii
0494-target-sum
0539-minimum-time-difference
0594-longest-harmonious-subsequence
0624-maximum-distance-in-arrays
0729-my-calendar-i
0731-my-calendar-ii
0825-max-increase-to-keep-city-skyline
0870-magic-squares-in-grid
0890-lemonade-change
0906-walking-robot-simulation
0921-spiral-matrix-iii
0943-sum-of-subarray-minimums
0948-sort-an-array
0952-word-subsets
0999-regions-cut-by-slashes
1002-maximum-width-ramp
1049-minimum-domino-rotations-for-equal-row
1063-best-sightseeing-pair
1207-delete-nodes-and-return-forest
1227-number-of-equivalent-domino-pairs
1240-stone-game-ii
1256-rank-transform-of-an-array
1293-three-consecutive-odds
1325-path-with-maximum-probability
1333-sort-the-jumbled-numbers
1335-maximum-candies-allocated-to-k-children
1364-tuple-with-same-product
1421-find-numbers-with-even-number-of-digits
1435-xor-queries-of-a-subarray
1468-check-if-n-and-its-double-exist
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1496-lucky-numbers-in-a-matrix
1510-find-lucky-integer-in-an-array
1511-count-number-of-teams
1524-string-matching-in-an-array
1556-make-two-arrays-equal-by-reversing-subarrays
1572-subrectangle-queries
1615-range-sum-of-sorted-subarray-sums
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1691-minimum-number-of-days-to-disconnect-island
1694-make-sum-divisible-by-p
1711-find-valid-matrix-given-row-and-column-sums
1720-crawler-log-folder
1741-sort-array-by-increasing-frequency
1755-defuse-the-bomb
1766-minimum-number-of-removals-to-make-mountain-array
1786-count-the-number-of-consistent-strings
1803-average-waiting-time
1886-minimum-limit-of-balls-in-a-bag
1923-sentence-similarity-iii
1940-maximum-xor-for-each-query
1951-find-the-winner-of-the-circular-game
2006-find-the-student-that-will-replace-the-chalk
2035-count-sub-islands
2054-the-number-of-the-smallest-unoccupied-chair
2067-maximum-number-of-points-with-cost
2099-number-of-strings-that-appear-as-substrings-in-word
2132-convert-1d-array-into-2d-array
2137-final-value-of-variable-after-performing-operations
2155-find-missing-observations
2163-kth-distinct-string-in-an-array
2164-two-best-non-overlapping-events
2180-maximum-number-of-tasks-you-can-assign
2215-finding-3-digit-even-numbers
2232-adding-spaces-to-a-string
2255-minimum-swaps-to-group-all-1s-together-ii
2292-counting-words-with-a-given-prefix
2306-create-binary-tree-from-descriptions
2343-count-unguarded-cells-in-the-grid
2394-count-subarrays-with-score-less-than-k
2411-spiral-matrix-iv
2465-shifting-letters-ii
2488-divide-intervals-into-minimum-number-of-groups
2494-sum-of-prefix-scores-of-strings
2502-sort-the-people
2503-longest-subarray-with-maximum-bitwise-and
2586-longest-square-streak-in-an-array
2614-maximum-count-of-positive-integer-and-negative-integer
2640-maximum-number-of-integers-to-choose-from-a-range-i
2665-minimum-time-to-repair-cars
2690-house-robber-iv
2755-extra-characters-in-a-string
2794-maximum-number-of-moves-in-a-grid
2846-robot-collisions
3235-minimum-cost-to-convert-string-i
3329-find-the-length-of-the-longest-common-prefix
3380-shortest-subarray-with-or-at-least-k-ii
3427-special-array-ii
3430-count-days-without-meetings
3476-find-minimum-operations-to-make-all-elements-divisible-by-three
3483-alternating-groups-ii
3501-delete-nodes-from-linked-list-present-in-array
3517-shortest-distance-after-road-addition-queries-i
3522-find-the-power-of-k-size-subarrays-i
3643-zero-array-transformation-ii
3685-count-subarrays-of-length-three-with-a-condition

Dynamic Programming

0064-minimum-path-sum
0120-triangle
0152-maximum-product-subarray
0241-different-ways-to-add-parentheses
0264-ugly-number-ii
0300-longest-increasing-subsequence
0322-coin-change
0494-target-sum
0650-2-keys-keyboard
0868-push-dominoes
0943-sum-of-subarray-minimums
1063-best-sightseeing-pair
1240-stone-game-ii
1456-find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance
1511-count-number-of-teams
1756-minimum-deletions-to-make-string-balanced
1766-minimum-number-of-removals-to-make-mountain-array
2067-maximum-number-of-points-with-cost
2164-two-best-non-overlapping-events
2586-longest-square-streak-in-an-array
2755-extra-characters-in-a-string
2794-maximum-number-of-moves-in-a-grid

Matrix

0048-rotate-image
0064-minimum-path-sum
0407-trapping-rain-water-ii
0825-max-increase-to-keep-city-skyline
0870-magic-squares-in-grid
0921-spiral-matrix-iii
0999-regions-cut-by-slashes
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1496-lucky-numbers-in-a-matrix
1572-subrectangle-queries
1691-minimum-number-of-days-to-disconnect-island
1711-find-valid-matrix-given-row-and-column-sums
2035-count-sub-islands
2132-convert-1d-array-into-2d-array
2343-count-unguarded-cells-in-the-grid
2411-spiral-matrix-iv
2794-maximum-number-of-moves-in-a-grid

Hash Table

0160-intersection-of-two-linked-lists
0219-contains-duplicate-ii
0264-ugly-number-ii
0350-intersection-of-two-arrays-ii
0567-permutation-in-string
0594-longest-harmonious-subsequence
0870-magic-squares-in-grid
0906-walking-robot-simulation
0920-uncommon-words-from-two-sentences
0952-word-subsets
0984-most-stones-removed-with-same-row-or-column
0999-regions-cut-by-slashes
1207-delete-nodes-and-return-forest
1227-number-of-equivalent-domino-pairs
1256-rank-transform-of-an-array
1364-tuple-with-same-product
1468-check-if-n-and-its-double-exist
1473-find-the-longest-substring-containing-vowels-in-even-counts
1510-find-lucky-integer-in-an-array
1556-make-two-arrays-equal-by-reversing-subarrays
1694-make-sum-divisible-by-p
1741-sort-array-by-increasing-frequency
1786-count-the-number-of-consistent-strings
2054-the-number-of-the-smallest-unoccupied-chair
2163-kth-distinct-string-in-an-array
2215-finding-3-digit-even-numbers
2306-create-binary-tree-from-descriptions
2502-sort-the-people
2586-longest-square-streak-in-an-array
2640-maximum-number-of-integers-to-choose-from-a-range-i
2755-extra-characters-in-a-string
3267-find-longest-special-substring-that-occurs-thrice-i
3276-minimum-number-of-pushes-to-type-word-ii
3329-find-the-length-of-the-longest-common-prefix
3412-permutation-difference-between-two-strings
3501-delete-nodes-from-linked-list-present-in-array
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Two Pointers

0015-3sum
0075-sort-colors
0148-sort-list
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0295-find-median-from-data-stream
0350-intersection-of-two-arrays-ii
0567-permutation-in-string
0868-push-dominoes
1468-check-if-n-and-its-double-exist
1566-check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence
1615-range-sum-of-sorted-subarray-sums
1923-sentence-similarity-iii
2095-minimum-number-of-swaps-to-make-the-string-balanced
2232-adding-spaces-to-a-string
2414-move-pieces-to-obtain-a-string
2481-strictly-palindromic-number
2488-divide-intervals-into-minimum-number-of-groups
3018-make-string-a-subsequence-using-cyclic-increments

Binary Search

0167-two-sum-ii-input-array-is-sorted
0300-longest-increasing-subsequence
0350-intersection-of-two-arrays-ii
0729-my-calendar-i
0731-my-calendar-ii
1335-maximum-candies-allocated-to-k-children
1468-check-if-n-and-its-double-exist
1615-range-sum-of-sorted-subarray-sums
1766-minimum-number-of-removals-to-make-mountain-array
1886-minimum-limit-of-balls-in-a-bag
2006-find-the-student-that-will-replace-the-chalk
2164-two-best-non-overlapping-events
2180-maximum-number-of-tasks-you-can-assign
2394-count-subarrays-with-score-less-than-k
2586-longest-square-streak-in-an-array
2614-maximum-count-of-positive-integer-and-negative-integer
2640-maximum-number-of-integers-to-choose-from-a-range-i
2665-minimum-time-to-repair-cars
2690-house-robber-iv
3267-find-longest-special-substring-that-occurs-thrice-i
3427-special-array-ii
3643-zero-array-transformation-ii

Sorting

0015-3sum
0075-sort-colors
0148-sort-list
0179-largest-number
0215-kth-largest-element-in-an-array
0295-find-median-from-data-stream
0350-intersection-of-two-arrays-ii
0539-minimum-time-difference
0594-longest-harmonious-subsequence
0948-sort-an-array
1256-rank-transform-of-an-array
1333-sort-the-jumbled-numbers
1468-check-if-n-and-its-double-exist
1556-make-two-arrays-equal-by-reversing-subarrays
1615-range-sum-of-sorted-subarray-sums
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1741-sort-array-by-increasing-frequency
2164-two-best-non-overlapping-events
2180-maximum-number-of-tasks-you-can-assign
2215-finding-3-digit-even-numbers
2488-divide-intervals-into-minimum-number-of-groups
2502-sort-the-people
2586-longest-square-streak-in-an-array
2640-maximum-number-of-integers-to-choose-from-a-range-i
2846-robot-collisions
3276-minimum-number-of-pushes-to-type-word-ii
3430-count-days-without-meetings

Greedy

0179-largest-number
0624-maximum-distance-in-arrays
0670-maximum-swap
0825-max-increase-to-keep-city-skyline
0890-lemonade-change
0957-minimum-add-to-make-parentheses-valid
1049-minimum-domino-rotations-for-equal-row
1616-minimum-difference-between-largest-and-smallest-value-in-three-moves
1711-find-valid-matrix-given-row-and-column-sums
1766-minimum-number-of-removals-to-make-mountain-array
1818-maximum-score-from-removing-substrings
2095-minimum-number-of-swaps-to-make-the-string-balanced
2180-maximum-number-of-tasks-you-can-assign
2488-divide-intervals-into-minimum-number-of-groups
2640-maximum-number-of-integers-to-choose-from-a-range-i
3276-minimum-number-of-pushes-to-type-word-ii

Linked List

0002-add-two-numbers
0148-sort-list
0160-intersection-of-two-linked-lists
0725-split-linked-list-in-parts
1484-linked-list-in-binary-tree
2182-find-the-minimum-and-maximum-number-of-nodes-between-critical-points
2299-merge-nodes-in-between-zeros
2411-spiral-matrix-iv
2903-insert-greatest-common-divisors-in-linked-list
3501-delete-nodes-from-linked-list-present-in-array

Simulation

0592-fraction-addition-and-subtraction
0906-walking-robot-simulation
0921-spiral-matrix-iii
1642-water-bottles
1667-find-kth-bit-in-nth-binary-string
1803-average-waiting-time
1951-find-the-winner-of-the-circular-game
2006-find-the-student-that-will-replace-the-chalk
2076-sum-of-digits-of-string-after-convert
2132-convert-1d-array-into-2d-array
2137-final-value-of-variable-after-performing-operations
2155-find-missing-observations
2232-adding-spaces-to-a-string
2299-merge-nodes-in-between-zeros
2343-count-unguarded-cells-in-the-grid
2411-spiral-matrix-iv
2645-pass-the-pillow
2846-robot-collisions
3447-clear-digits
3600-find-the-k-th-character-in-string-game-i

Math

0002-add-two-numbers
0048-rotate-image
0189-rotate-array
0241-different-ways-to-add-parentheses
0264-ugly-number-ii
0273-integer-to-english-words
0539-minimum-time-difference
0564-find-the-closest-palindrome
0592-fraction-addition-and-subtraction
0650-2-keys-keyboard
0670-maximum-swap
0870-magic-squares-in-grid
1240-stone-game-ii
1421-find-numbers-with-even-number-of-digits
1642-water-bottles
1951-find-the-winner-of-the-circular-game
2155-find-missing-observations
2481-strictly-palindromic-number
2610-closest-prime-numbers-in-range
2630-alternating-digit-sum
2645-pass-the-pillow
2903-insert-greatest-common-divisors-in-linked-list
3476-find-minimum-operations-to-make-all-elements-divisible-by-three
3600-find-the-k-th-character-in-string-game-i
3601-find-the-k-th-character-in-string-game-ii

Recursion

0002-add-two-numbers
0241-different-ways-to-add-parentheses
0273-integer-to-english-words
1667-find-kth-bit-in-nth-binary-string
1951-find-the-winner-of-the-circular-game
3600-find-the-k-th-character-in-string-game-i
3601-find-the-k-th-character-in-string-game-ii

Queue

1951-find-the-winner-of-the-circular-game
2180-maximum-number-of-tasks-you-can-assign

String

0179-largest-number
0214-shortest-palindrome
0241-different-ways-to-add-parentheses
0273-integer-to-english-words
0539-minimum-time-difference
0564-find-the-closest-palindrome
0567-permutation-in-string
0592-fraction-addition-and-subtraction
0812-rotate-string
0868-push-dominoes
0920-uncommon-words-from-two-sentences
0952-word-subsets
0957-minimum-add-to-make-parentheses-valid
1205-defanging-an-ip-address
1298-reverse-substrings-between-each-pair-of-parentheses
1473-find-the-longest-substring-containing-vowels-in-even-counts
1524-string-matching-in-an-array
1537-maximum-score-after-splitting-a-string
1566-check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence
1667-find-kth-bit-in-nth-binary-string
1720-crawler-log-folder
1756-minimum-deletions-to-make-string-balanced
1786-count-the-number-of-consistent-strings
1818-maximum-score-from-removing-substrings
1923-sentence-similarity-iii
2076-sum-of-digits-of-string-after-convert
2095-minimum-number-of-swaps-to-make-the-string-balanced
2099-number-of-strings-that-appear-as-substrings-in-word
2137-final-value-of-variable-after-performing-operations
2163-kth-distinct-string-in-an-array
2217-step-by-step-directions-from-a-binary-tree-node-to-another
2232-adding-spaces-to-a-string
2292-counting-words-with-a-given-prefix
2414-move-pieces-to-obtain-a-string
2463-minimum-recolors-to-get-k-consecutive-black-blocks
2465-shifting-letters-ii
2494-sum-of-prefix-scores-of-strings
2502-sort-the-people
2580-circular-sentence
2755-extra-characters-in-a-string
3018-make-string-a-subsequence-using-cyclic-increments
3174-minimum-number-of-changes-to-make-binary-string-beautiful
3235-minimum-cost-to-convert-string-i
3267-find-longest-special-substring-that-occurs-thrice-i
3276-minimum-number-of-pushes-to-type-word-ii
3329-find-the-length-of-the-longest-common-prefix
3379-score-of-a-string
3412-permutation-difference-between-two-strings
3447-clear-digits
3451-string-compression-iii
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Stack

0145-binary-tree-postorder-traversal
0776-n-ary-tree-postorder-traversal
0943-sum-of-subarray-minimums
0957-minimum-add-to-make-parentheses-valid
1002-maximum-width-ramp
1298-reverse-substrings-between-each-pair-of-parentheses
1720-crawler-log-folder
1756-minimum-deletions-to-make-string-balanced
1818-maximum-score-from-removing-substrings
2095-minimum-number-of-swaps-to-make-the-string-balanced
2846-robot-collisions
3447-clear-digits

Tree

0098-validate-binary-search-tree
0145-binary-tree-postorder-traversal
0776-n-ary-tree-postorder-traversal
0789-kth-largest-element-in-a-stream
1207-delete-nodes-and-return-forest
1484-linked-list-in-binary-tree
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
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level

Depth-First Search

0098-validate-binary-search-tree
0145-binary-tree-postorder-traversal
0386-lexicographical-numbers
0776-n-ary-tree-postorder-traversal
0984-most-stones-removed-with-same-row-or-column
0999-regions-cut-by-slashes
1207-delete-nodes-and-return-forest
1484-linked-list-in-binary-tree
1653-number-of-good-leaf-nodes-pairs
1691-minimum-number-of-days-to-disconnect-island
2035-count-sub-islands
2217-step-by-step-directions-from-a-binary-tree-node-to-another

Binary Search Tree

0098-validate-binary-search-tree
0789-kth-largest-element-in-a-stream

Binary Tree

0098-validate-binary-search-tree
0145-binary-tree-postorder-traversal
0789-kth-largest-element-in-a-stream
1207-delete-nodes-and-return-forest
1484-linked-list-in-binary-tree
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
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level

Brainteaser

2481-strictly-palindromic-number
2503-longest-subarray-with-maximum-bitwise-and

Divide and Conquer

0148-sort-list
0215-kth-largest-element-in-an-array
0948-sort-an-array

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0264-ugly-number-ii
0295-find-median-from-data-stream
0407-trapping-rain-water-ii
0789-kth-largest-element-in-a-stream
0948-sort-an-array
1325-path-with-maximum-probability
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
2054-the-number-of-the-smallest-unoccupied-chair
2164-two-best-non-overlapping-events
2488-divide-intervals-into-minimum-number-of-groups
2803-modify-graph-edge-weights

Merge Sort

0148-sort-list
0948-sort-an-array

Bucket Sort

0948-sort-an-array

Radix Sort

0948-sort-an-array

Counting Sort

0594-longest-harmonious-subsequence
0920-uncommon-words-from-two-sentences
0948-sort-an-array
1227-number-of-equivalent-domino-pairs
1364-tuple-with-same-product
1510-find-lucky-integer-in-an-array
1786-count-the-number-of-consistent-strings
2163-kth-distinct-string-in-an-array
2494-sum-of-prefix-scores-of-strings
2614-maximum-count-of-positive-integer-and-negative-integer
3267-find-longest-special-substring-that-occurs-thrice-i
3276-minimum-number-of-pushes-to-type-word-ii

Graph

0984-most-stones-removed-with-same-row-or-column
1325-path-with-maximum-probability
1456-find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
2803-modify-graph-edge-weights
3235-minimum-cost-to-convert-string-i
3517-shortest-distance-after-road-addition-queries-i

Shortest Path

1325-path-with-maximum-probability
1456-find-the-city-with-the-smallest-number-of-neighbors-at-a-threshold-distance
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
2803-modify-graph-edge-weights
3235-minimum-cost-to-convert-string-i

Binary Indexed Tree

1511-count-number-of-teams

Sliding Window

0219-contains-duplicate-ii
0567-permutation-in-string
0594-longest-harmonious-subsequence
1755-defuse-the-bomb
2255-minimum-swaps-to-group-all-1s-together-ii
2394-count-subarrays-with-score-less-than-k
2463-minimum-recolors-to-get-k-consecutive-black-blocks
3267-find-longest-special-substring-that-occurs-thrice-i
3380-shortest-subarray-with-or-at-least-k-ii
3483-alternating-groups-ii
3522-find-the-power-of-k-size-subarrays-i
3569-count-of-substrings-containing-every-vowel-and-k-consonants-ii

Breadth-First Search

0322-coin-change
0407-trapping-rain-water-ii
0999-regions-cut-by-slashes
1484-linked-list-in-binary-tree
1485-minimum-cost-to-make-at-least-one-valid-path-in-a-grid
1691-minimum-number-of-days-to-disconnect-island
2035-count-sub-islands
2558-minimum-number-of-operations-to-sort-a-binary-tree-by-level
3517-shortest-distance-after-road-addition-queries-i

Union Find

0984-most-stones-removed-with-same-row-or-column
0999-regions-cut-by-slashes
2035-count-sub-islands

Design

0295-find-median-from-data-stream
0729-my-calendar-i
0731-my-calendar-ii
0789-kth-largest-element-in-a-stream
1572-subrectangle-queries

Data Stream

0295-find-median-from-data-stream
0789-kth-largest-element-in-a-stream

Backtracking

0039-combination-sum
0040-combination-sum-ii
0494-target-sum

Prefix Sum

0731-my-calendar-ii
1240-stone-game-ii
1435-xor-queries-of-a-subarray
1473-find-the-longest-substring-containing-vowels-in-even-counts
1537-maximum-score-after-splitting-a-string
1694-make-sum-divisible-by-p
1940-maximum-xor-for-each-query
2006-find-the-student-that-will-replace-the-chalk
2394-count-subarrays-with-score-less-than-k
2465-shifting-letters-ii
2488-divide-intervals-into-minimum-number-of-groups
3427-special-array-ii
3643-zero-array-transformation-ii

Game Theory

1240-stone-game-ii

Bit Manipulation

0476-number-complement
1435-xor-queries-of-a-subarray
1473-find-the-longest-substring-containing-vowels-in-even-counts
1786-count-the-number-of-consistent-strings
1940-maximum-xor-for-each-query
2323-minimum-bit-flips-to-convert-number
2503-longest-subarray-with-maximum-bitwise-and
3380-shortest-subarray-with-or-at-least-k-ii
3394-minimum-array-end
3600-find-the-k-th-character-in-string-game-i
3601-find-the-k-th-character-in-string-game-ii

Strongly Connected Component

1691-minimum-number-of-days-to-disconnect-island

Quickselect

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

Number Theory

2610-closest-prime-numbers-in-range
2903-insert-greatest-common-divisors-in-linked-list

Memoization

0241-different-ways-to-add-parentheses

Rolling Hash

0214-shortest-palindrome

String Matching

0214-shortest-palindrome
0812-rotate-string
1524-string-matching-in-an-array
1566-check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence
2292-counting-words-with-a-given-prefix

Hash Function

0214-shortest-palindrome

Trie

0386-lexicographical-numbers
0440-k-th-smallest-in-lexicographical-order
2494-sum-of-prefix-scores-of-strings
2755-extra-characters-in-a-string
3329-find-the-length-of-the-longest-common-prefix

Segment Tree

0729-my-calendar-i
0731-my-calendar-ii

Ordered Set

0729-my-calendar-i
0731-my-calendar-ii

Monotonic Stack

0943-sum-of-subarray-minimums
1002-maximum-width-ramp

Database

0175-combine-two-tables

Monotonic Queue

2180-maximum-number-of-tasks-you-can-assign

Enumeration

2215-finding-3-digit-even-numbers