Leetcode-Problems

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

LeetCode Topics

Binary Search

0004-median-of-two-sorted-arrays
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0069-sqrtx
0074-search-a-2d-matrix
0081-search-in-rotated-sorted-array-ii
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0240-search-a-2d-matrix-ii
0278-first-bad-version
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0350-intersection-of-two-arrays-ii
0713-subarray-product-less-than-k
0792-binary-search

Interactive

0278-first-bad-version

Math

0002-add-two-numbers
0050-powx-n
0062-unique-paths
0069-sqrtx
0070-climbing-stairs
0202-happy-number
0231-power-of-two
0263-ugly-number
0380-insert-delete-getrandom-o1
0564-find-the-closest-palindrome
0628-maximum-product-of-three-numbers
0728-self-dividing-numbers
1013-fibonacci-number
1018-largest-perimeter-triangle
1236-n-th-tribonacci-number
1411-convert-binary-number-in-a-linked-list-to-integer
1477-product-of-the-last-k-numbers
1631-number-of-sub-arrays-with-odd-sum
2032-largest-odd-number-in-string
2448-count-number-of-bad-pairs
2802-find-the-punishment-number-of-an-integer
3201-distribute-candies-among-children-ii
3227-find-missing-and-repeated-values

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0014-longest-common-prefix
0022-generate-parentheses
0038-count-and-say
0071-simplify-path
0079-word-search
0125-valid-palindrome
0151-reverse-words-in-a-string
0205-isomorphic-strings
0242-valid-anagram
0345-reverse-vowels-of-a-string
0387-first-unique-character-in-a-string
0394-decode-string
0443-string-compression
0451-sort-characters-by-frequency
0564-find-the-closest-palindrome
0567-permutation-in-string
0647-palindromic-substrings
0812-rotate-string
0874-backspace-string-compare
0952-word-subsets
0957-minimum-add-to-make-parentheses-valid
1093-recover-a-tree-from-preorder-traversal
1128-remove-all-adjacent-duplicates-in-string
1160-letter-tile-possibilities
1170-shortest-common-supersequence
1250-longest-common-subsequence
1460-number-of-substrings-containing-all-three-characters
1502-construct-k-palindrome-strings
1516-the-k-th-lexicographical-string-of-all-happy-strings-of-length-n
1904-second-largest-digit-in-a-string
1915-check-if-one-string-swap-can-make-strings-equal
2021-remove-all-occurrences-of-a-substring
2032-largest-odd-number-in-string
2292-counting-words-with-a-given-prefix
2456-construct-smallest-number-from-di-string
2502-sort-the-people
3174-minimum-number-of-changes-to-make-binary-string-beautiful
3309-count-prefix-and-suffix-pairs-i
3455-minimum-length-of-string-after-operations

Greedy

0011-container-with-most-water
0045-jump-game-ii
0055-jump-game
0122-best-time-to-buy-and-sell-stock-ii
0134-gas-station
0135-candy
0334-increasing-triplet-subsequence
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0455-assign-cookies
0890-lemonade-change
0957-minimum-add-to-make-parentheses-valid
0982-minimum-increment-to-make-array-unique
1018-largest-perimeter-triangle
1346-maximize-the-topmost-element-after-k-moves
1502-construct-k-palindrome-strings
2032-largest-odd-number-in-string
2212-removing-minimum-and-maximum-from-array
2456-construct-smallest-number-from-di-string
2509-minimize-xor

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0041-first-missing-positive
0073-set-matrix-zeroes
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0160-intersection-of-two-linked-lists
0169-majority-element
0202-happy-number
0205-isomorphic-strings
0217-contains-duplicate
0219-contains-duplicate-ii
0242-valid-anagram
0350-intersection-of-two-arrays-ii
0380-insert-delete-getrandom-o1
0387-first-unique-character-in-a-string
0451-sort-characters-by-frequency
0496-next-greater-element-i
0560-subarray-sum-equals-k
0567-permutation-in-string
0575-distribute-candies
0905-length-of-longest-fibonacci-subsequence
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0940-fruit-into-baskets
0952-word-subsets
1160-letter-tile-possibilities
1364-tuple-with-same-product
1387-find-elements-in-a-contaminated-binary-tree
1460-number-of-substrings-containing-all-three-characters
1502-construct-k-palindrome-strings
1741-sort-array-by-increasing-frequency
1798-max-number-of-k-sum-pairs
1904-second-largest-digit-in-a-string
1915-check-if-one-string-swap-can-make-strings-equal
2308-divide-array-into-equal-pairs
2331-intersection-of-multiple-arrays
2434-design-a-number-container-system
2448-count-number-of-bad-pairs
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2502-sort-the-people
2707-merge-two-2d-arrays-by-summing-values
2766-find-the-prefix-common-array-of-two-arrays
3227-find-missing-and-repeated-values
3434-find-the-number-of-distinct-colors-among-the-balls
3455-minimum-length-of-string-after-operations

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0050-powx-n
0143-reorder-list
0231-power-of-two
0394-decode-string
1013-fibonacci-number

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
0014-longest-common-prefix
0015-3sum
0027-remove-element
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0039-combination-sum
0040-combination-sum-ii
0041-first-missing-positive
0042-trapping-rain-water
0045-jump-game-ii
0047-permutations-ii
0051-n-queens
0053-maximum-subarray
0054-spiral-matrix
0055-jump-game
0056-merge-intervals
0057-insert-interval
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0079-word-search
0081-search-in-rotated-sorted-array-ii
0088-merge-sorted-array
0090-subsets-ii
0122-best-time-to-buy-and-sell-stock-ii
0134-gas-station
0135-candy
0136-single-number
0152-maximum-product-subarray
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0198-house-robber
0200-number-of-islands
0209-minimum-size-subarray-sum
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0219-contains-duplicate-ii
0238-product-of-array-except-self
0240-search-a-2d-matrix-ii
0283-move-zeroes
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0322-coin-change
0334-increasing-triplet-subsequence
0350-intersection-of-two-arrays-ii
0380-insert-delete-getrandom-o1
0435-non-overlapping-intervals
0452-minimum-number-of-arrows-to-burst-balloons
0455-assign-cookies
0463-island-perimeter
0494-target-sum
0496-next-greater-element-i
0498-diagonal-traverse
0506-relative-ranks
0518-coin-change-ii
0560-subarray-sum-equals-k
0575-distribute-candies
0628-maximum-product-of-three-numbers
0665-non-decreasing-array
0713-subarray-product-less-than-k
0724-find-pivot-index
0735-asteroid-collision
0747-min-cost-climbing-stairs
0792-binary-search
0890-lemonade-change
0905-length-of-longest-fibonacci-subsequence
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0940-fruit-into-baskets
0943-sum-of-subarray-minimums
0948-sort-an-array
0952-word-subsets
0982-minimum-increment-to-make-array-unique
1018-largest-perimeter-triangle
1050-construct-binary-search-tree-from-preorder-traversal
1105-uncrossed-lines
1346-maximize-the-topmost-element-after-k-moves
1364-tuple-with-same-product
1424-maximum-candies-you-can-get-from-boxes
1477-product-of-the-last-k-numbers
1631-number-of-sub-arrays-with-odd-sum
1741-sort-array-by-increasing-frequency
1769-get-maximum-in-generated-array
1798-max-number-of-k-sum-pairs
1819-construct-the-lexicographically-largest-valid-sequence
1839-decode-xored-array
1849-maximum-absolute-sum-of-any-subarray
1878-check-if-array-is-sorted-and-rotated
1927-maximum-ascending-subarray-sum
2181-smallest-index-with-equal-value
2212-removing-minimum-and-maximum-from-array
2265-partition-array-according-to-given-pivot
2292-counting-words-with-a-given-prefix
2308-divide-array-into-equal-pairs
2331-intersection-of-multiple-arrays
2350-find-closest-number-to-zero
2448-count-number-of-bad-pairs
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2478-longest-nice-subarray
2502-sort-the-people
2533-bitwise-xor-of-all-pairings
2707-merge-two-2d-arrays-by-summing-values
2764-maximum-number-of-fish-in-a-grid
2766-find-the-prefix-common-array-of-two-arrays
2792-neighboring-bitwise-xor
3227-find-missing-and-repeated-values
3309-count-prefix-and-suffix-pairs-i
3332-minimum-operations-to-exceed-threshold-value-ii
3372-longest-strictly-increasing-or-strictly-decreasing-subarray
3429-special-array-i
3434-find-the-number-of-distinct-colors-among-the-balls
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Depth-First Search

0079-word-search
0094-binary-tree-inorder-traversal
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0463-island-perimeter
0543-diameter-of-binary-tree
0563-binary-tree-tilt
0617-merge-two-binary-trees
0684-redundant-connection
0801-is-graph-bipartite
0820-find-eventual-safe-states
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree
2764-maximum-number-of-fish-in-a-grid

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0111-minimum-depth-of-binary-tree
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0322-coin-change
0463-island-perimeter
0617-merge-two-binary-trees
0684-redundant-connection
0801-is-graph-bipartite
0820-find-eventual-safe-states
1387-find-elements-in-a-contaminated-binary-tree
1424-maximum-candies-you-can-get-from-boxes
2764-maximum-number-of-fish-in-a-grid

Matrix

0054-spiral-matrix
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0079-word-search
0200-number-of-islands
0240-search-a-2d-matrix-ii
0463-island-perimeter
0498-diagonal-traverse
2764-maximum-number-of-fish-in-a-grid
3227-find-missing-and-repeated-values

String Matching

0812-rotate-string
2292-counting-words-with-a-given-prefix
3309-count-prefix-and-suffix-pairs-i

Sorting

0015-3sum
0047-permutations-ii
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0242-valid-anagram
0350-intersection-of-two-arrays-ii
0435-non-overlapping-intervals
0451-sort-characters-by-frequency
0452-minimum-number-of-arrows-to-burst-balloons
0455-assign-cookies
0506-relative-ranks
0628-maximum-product-of-three-numbers
0948-sort-an-array
0982-minimum-increment-to-make-array-unique
1018-largest-perimeter-triangle
1741-sort-array-by-increasing-frequency
1798-max-number-of-k-sum-pairs
2331-intersection-of-multiple-arrays
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2502-sort-the-people

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0451-sort-characters-by-frequency
0506-relative-ranks
0948-sort-an-array
2434-design-a-number-container-system
2473-max-sum-of-a-pair-with-equal-sum-of-digits
3332-minimum-operations-to-exceed-threshold-value-ii

Bucket Sort

0451-sort-characters-by-frequency
0948-sort-an-array

Counting

0169-majority-element
0387-first-unique-character-in-a-string
0451-sort-characters-by-frequency
0982-minimum-increment-to-make-array-unique
1160-letter-tile-possibilities
1364-tuple-with-same-product
1502-construct-k-palindrome-strings
1915-check-if-one-string-swap-can-make-strings-equal
2308-divide-array-into-equal-pairs
2331-intersection-of-multiple-arrays
2448-count-number-of-bad-pairs
3455-minimum-length-of-string-after-operations

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0019-remove-nth-node-from-end-of-list
0027-remove-element
0042-trapping-rain-water
0075-sort-colors
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0151-reverse-words-in-a-string
0160-intersection-of-two-linked-lists
0167-two-sum-ii-input-array-is-sorted
0202-happy-number
0283-move-zeroes
0287-find-the-duplicate-number
0345-reverse-vowels-of-a-string
0350-intersection-of-two-arrays-ii
0443-string-compression
0455-assign-cookies
0567-permutation-in-string
0647-palindromic-substrings
0874-backspace-string-compare
0908-middle-of-the-linked-list
1798-max-number-of-k-sum-pairs
2265-partition-array-according-to-given-pivot
2707-merge-two-2d-arrays-by-summing-values

Dynamic Programming

0005-longest-palindromic-substring
0022-generate-parentheses
0042-trapping-rain-water
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0122-best-time-to-buy-and-sell-stock-ii
0152-maximum-product-subarray
0198-house-robber
0213-house-robber-ii
0300-longest-increasing-subsequence
0322-coin-change
0338-counting-bits
0435-non-overlapping-intervals
0494-target-sum
0518-coin-change-ii
0647-palindromic-substrings
0747-min-cost-climbing-stairs
0905-length-of-longest-fibonacci-subsequence
0943-sum-of-subarray-minimums
1013-fibonacci-number
1105-uncrossed-lines
1170-shortest-common-supersequence
1236-n-th-tribonacci-number
1250-longest-common-subsequence
1631-number-of-sub-arrays-with-odd-sum
1849-maximum-absolute-sum-of-any-subarray

Combinatorics

0062-unique-paths
3201-distribute-candies-among-children-ii

Stack

0042-trapping-rain-water
0071-simplify-path
0094-binary-tree-inorder-traversal
0143-reorder-list
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0155-min-stack
0232-implement-queue-using-stacks
0394-decode-string
0496-next-greater-element-i
0735-asteroid-collision
0874-backspace-string-compare
0943-sum-of-subarray-minimums
0957-minimum-add-to-make-parentheses-valid
1050-construct-binary-search-tree-from-preorder-traversal
1128-remove-all-adjacent-duplicates-in-string
2021-remove-all-occurrences-of-a-substring
2456-construct-smallest-number-from-di-string

Monotonic Stack

0042-trapping-rain-water
0496-next-greater-element-i
0943-sum-of-subarray-minimums
1050-construct-binary-search-tree-from-preorder-traversal

Backtracking

0022-generate-parentheses
0039-combination-sum
0040-combination-sum-ii
0047-permutations-ii
0051-n-queens
0078-subsets
0079-word-search
0090-subsets-ii
0494-target-sum
1160-letter-tile-possibilities
1516-the-k-th-lexicographical-string-of-all-happy-strings-of-length-n
1819-construct-the-lexicographically-largest-valid-sequence
2456-construct-smallest-number-from-di-string
2802-find-the-punishment-number-of-an-integer

Bit Manipulation

0078-subsets
0090-subsets-ii
0136-single-number
0190-reverse-bits
0191-number-of-1-bits
0201-bitwise-and-of-numbers-range
0231-power-of-two
0287-find-the-duplicate-number
0338-counting-bits
1839-decode-xored-array
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
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Sliding Window

0003-longest-substring-without-repeating-characters
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0567-permutation-in-string
0713-subarray-product-less-than-k
0940-fruit-into-baskets
1460-number-of-substrings-containing-all-three-characters
2478-longest-nice-subarray
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0560-subarray-sum-equals-k
0713-subarray-product-less-than-k
0724-find-pivot-index
1477-product-of-the-last-k-numbers
1631-number-of-sub-arrays-with-odd-sum
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Divide and Conquer

0004-median-of-two-sorted-arrays
0023-merge-k-sorted-lists
0053-maximum-subarray
0169-majority-element
0190-reverse-bits
0191-number-of-1-bits
0215-kth-largest-element-in-an-array
0240-search-a-2d-matrix-ii
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0948-sort-an-array

Merge Sort

0023-merge-k-sorted-lists
0948-sort-an-array

Radix Sort

0948-sort-an-array

Counting Sort

0948-sort-an-array

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
0083-remove-duplicates-from-sorted-list
0092-reverse-linked-list-ii
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0143-reorder-list
0160-intersection-of-two-linked-lists
0328-odd-even-linked-list
0908-middle-of-the-linked-list
1411-convert-binary-number-in-a-linked-list-to-integer

Trie

0014-longest-common-prefix
3309-count-prefix-and-suffix-pairs-i

Rolling Hash

3309-count-prefix-and-suffix-pairs-i

Hash Function

3309-count-prefix-and-suffix-pairs-i

Queue

0232-implement-queue-using-stacks
0387-first-unique-character-in-a-string
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i

Quickselect

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

Database

0175-combine-two-tables
0176-second-highest-salary
1153-product-sales-analysis-i

Union Find

0200-number-of-islands
0684-redundant-connection
0801-is-graph-bipartite
2764-maximum-number-of-fish-in-a-grid

Graph

0207-course-schedule
0210-course-schedule-ii
0684-redundant-connection
0801-is-graph-bipartite
0820-find-eventual-safe-states
1424-maximum-candies-you-can-get-from-boxes

Brainteaser

2533-bitwise-xor-of-all-pairings

Topological Sort

0207-course-schedule
0210-course-schedule-ii
0820-find-eventual-safe-states

Simulation

0054-spiral-matrix
0498-diagonal-traverse
0735-asteroid-collision
0874-backspace-string-compare
1769-get-maximum-in-generated-array
2021-remove-all-occurrences-of-a-substring
2265-partition-array-according-to-given-pivot
3332-minimum-operations-to-exceed-threshold-value-ii
3434-find-the-number-of-distinct-colors-among-the-balls

Design

0155-min-stack
0232-implement-queue-using-stacks
0380-insert-delete-getrandom-o1
1387-find-elements-in-a-contaminated-binary-tree
1477-product-of-the-last-k-numbers
2434-design-a-number-container-system

Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0543-diameter-of-binary-tree
0563-binary-tree-tilt
0617-merge-two-binary-trees
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1050-construct-binary-search-tree-from-preorder-traversal
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree

Binary Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0226-invert-binary-tree
0235-lowest-common-ancestor-of-a-binary-search-tree
0236-lowest-common-ancestor-of-a-binary-tree
0543-diameter-of-binary-tree
0563-binary-tree-tilt
0617-merge-two-binary-trees
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1050-construct-binary-search-tree-from-preorder-traversal
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree

Ordered Set

2434-design-a-number-container-system

Data Stream

1477-product-of-the-last-k-numbers

Binary Search Tree

0235-lowest-common-ancestor-of-a-binary-search-tree
1050-construct-binary-search-tree-from-preorder-traversal

Memoization

0070-climbing-stairs
1013-fibonacci-number
1236-n-th-tribonacci-number

Enumeration

3201-distribute-candies-among-children-ii

Randomized

0380-insert-delete-getrandom-o1