leetcode

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

LeetCode Topics

Linked List

0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0061-rotate-list
0083-remove-duplicates-from-sorted-list
0141-linked-list-cycle
0148-sort-list
0206-reverse-linked-list
0237-delete-node-in-a-linked-list
0876-middle-of-the-linked-list

Recursion

0021-merge-two-sorted-lists
0206-reverse-linked-list
0231-power-of-two
0342-power-of-four
0394-decode-string
1013-fibonacci-number

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0014-longest-common-prefix
0020-valid-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0058-length-of-last-word
0065-valid-number
0125-valid-palindrome
0151-reverse-words-in-a-string
0165-compare-version-numbers
0168-excel-sheet-column-title
0171-excel-sheet-column-number
0179-largest-number
0242-valid-anagram
0290-word-pattern
0344-reverse-string
0345-reverse-vowels-of-a-string
0383-ransom-note
0387-first-unique-character-in-a-string
0394-decode-string
0409-longest-palindrome
0412-fizz-buzz
0434-number-of-segments-in-a-string
0541-reverse-string-ii
0657-robot-return-to-origin
0709-to-lower-case
0771-jewels-and-stones
0804-unique-morse-code-words
0819-most-common-word
1189-maximum-number-of-balloons
1358-number-of-substrings-containing-all-three-characters
1374-generate-a-string-with-characters-that-have-odd-counts
1404-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1408-string-matching-in-an-array
1700-minimum-time-to-make-rope-colorful
1894-merge-strings-alternately
1927-sum-game
2000-reverse-prefix-of-word
2053-check-if-all-characters-have-equal-number-of-occurrences
2346-largest-3-same-digit-number-in-string
2390-removing-stars-from-a-string
2515-shortest-distance-to-target-string-in-a-circular-array
2839-check-if-strings-can-be-made-equal-with-operations-i
3227-vowels-game-in-a-string
3340-check-balanced-string
3396-valid-word
3407-substring-matching-pattern
3498-reverse-degree-of-a-string
3612-process-string-with-special-operations-i
3614-process-string-with-special-operations-ii
3872-find-most-frequent-vowel-and-consonant

Math

0007-reverse-integer
0009-palindrome-number
0029-divide-two-integers
0048-rotate-image
0066-plus-one
0069-sqrtx
0070-climbing-stairs
0168-excel-sheet-column-title
0171-excel-sheet-column-number
0189-rotate-array
0202-happy-number
0204-count-primes
0231-power-of-two
0258-add-digits
0263-ugly-number
0292-nim-game
0342-power-of-four
0367-valid-perfect-square
0371-sum-of-two-integers
0396-rotate-function
0412-fizz-buzz
0628-maximum-product-of-three-numbers
0728-self-dividing-numbers
0788-rotated-digits
0812-largest-triangle-area
0836-rectangle-overlap
0877-stone-game
0976-largest-perimeter-triangle
1013-fibonacci-number
1025-divisor-game
1137-n-th-tribonacci-number
1401-circle-and-rectangle-overlapping
1512-number-of-good-pairs
1642-water-bottles
1925-count-square-sum-triples
1927-sum-game
1952-three-divisors
2169-count-operations-to-obtain-zero
2177-find-three-consecutive-integers-that-sum-to-a-given-number
2238-a-number-after-a-double-reversal
2427-number-of-common-factors
2520-count-the-digits-that-divide-a-number
2535-difference-between-element-sum-and-digit-sum-of-an-array
2614-prime-in-diagonal
2652-sum-multiples
2769-find-the-maximum-achievable-number
2965-find-missing-and-repeated-values
3115-maximum-prime-difference
3190-find-minimum-operations-to-make-all-elements-divisible-by-three
3227-vowels-game-in-a-string
3289-the-two-sneaky-numbers-of-digitville
3321-type-of-triangle
3345-smallest-divisible-digit-product-i
3370-smallest-number-with-all-set-bits
3432-count-partitions-with-even-sum-difference
3492-maximum-containers-on-a-ship
3622-check-divisibility-by-digit-sum-and-product
3658-gcd-of-odd-and-even-sums
3783-mirror-distance-of-an-integer
3867-sum-of-gcd-of-formed-pairs
3870-count-commas-in-range
3876-construct-uniform-parity-array-ii

Binary Search

0069-sqrtx
0074-search-a-2d-matrix
0162-find-peak-element
0222-count-complete-tree-nodes
0278-first-bad-version
0287-find-the-duplicate-number
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0367-valid-perfect-square
0378-kth-smallest-element-in-a-sorted-matrix
0611-valid-triangle-number
1346-check-if-n-and-its-double-exist
1351-count-negative-numbers-in-a-sorted-matrix
3790-fruits-into-baskets-ii

Array

0001-two-sum
0014-longest-common-prefix
0015-3sum
0027-remove-element
0039-combination-sum
0042-trapping-rain-water
0048-rotate-image
0053-maximum-subarray
0054-spiral-matrix
0064-minimum-path-sum
0066-plus-one
0074-search-a-2d-matrix
0078-subsets
0088-merge-sorted-array
0108-convert-sorted-array-to-binary-search-tree
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0128-longest-consecutive-sequence
0135-candy
0136-single-number
0162-find-peak-element
0169-majority-element
0179-largest-number
0189-rotate-array
0204-count-primes
0217-contains-duplicate
0219-contains-duplicate-ii
0283-move-zeroes
0287-find-the-duplicate-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0378-kth-smallest-element-in-a-sorted-matrix
0396-rotate-function
0414-third-maximum-number
0442-find-all-duplicates-in-an-array
0448-find-all-numbers-disappeared-in-an-array
0455-assign-cookies
0485-max-consecutive-ones
0498-diagonal-traverse
0560-subarray-sum-equals-k
0561-array-partition
0566-reshape-the-matrix
0611-valid-triangle-number
0628-maximum-product-of-three-numbers
0643-maximum-average-subarray-i
0682-baseball-game
0717-1-bit-and-2-bit-characters
0746-min-cost-climbing-stairs
0804-unique-morse-code-words
0812-largest-triangle-area
0819-most-common-word
0867-transpose-matrix
0877-stone-game
0961-n-repeated-element-in-size-2n-array
0976-largest-perimeter-triangle
0977-squares-of-a-sorted-array
1137-height-checker
1200-minimum-absolute-difference
1293-three-consecutive-odds
1346-check-if-n-and-its-double-exist
1351-count-negative-numbers-in-a-sorted-matrix
1408-string-matching-in-an-array
1431-kids-with-the-greatest-number-of-candies
1480-running-sum-of-1d-array
1512-number-of-good-pairs
1582-special-positions-in-a-binary-matrix
1700-minimum-time-to-make-rope-colorful
1732-find-the-highest-altitude
1813-maximum-erasure-value
1848-minimum-distance-to-the-target-element
1877-minimize-maximum-pair-sum-in-array
1886-determine-whether-matrix-can-be-obtained-by-rotation
1929-concatenation-of-array
2112-minimum-difference-between-highest-and-lowest-of-k-scores
2144-minimum-cost-of-buying-candies-with-discount
2164-sort-even-and-odd-indices-independently
2215-find-the-difference-of-two-arrays
2460-apply-operations-to-an-array
2515-shortest-distance-to-target-string-in-a-circular-array
2535-difference-between-element-sum-and-digit-sum-of-an-array
2553-separate-the-digits-in-an-array
2614-prime-in-diagonal
2870-minimum-number-of-operations-to-make-array-empty
2965-find-missing-and-repeated-values
3010-divide-an-array-into-subarrays-with-minimum-cost-i
3069-distribute-elements-into-two-arrays-i
3115-maximum-prime-difference
3142-check-if-grid-satisfies-conditions
3190-find-minimum-operations-to-make-all-elements-divisible-by-three
3289-the-two-sneaky-numbers-of-digitville
3320-maximum-number-of-operations-with-the-same-score-i
3321-type-of-triangle
3432-count-partitions-with-even-sum-difference
3568-minimum-moves-to-clean-the-classroom
3701-compute-alternating-sum
3718-smallest-missing-multiple-of-k
3731-find-missing-elements
3788-maximum-unique-subarray-sum-after-deletion
3790-fruits-into-baskets-ii
3867-sum-of-gcd-of-formed-pairs
3876-construct-uniform-parity-array-ii

Database

0175-combine-two-tables
0176-second-highest-salary
0182-duplicate-emails
0197-rising-temperature
0570-managers-with-at-least-5-direct-reports
0577-employee-bonus
0607-sales-person
0620-not-boring-movies
0627-swap-sex-of-employees
1075-project-employees-i
1407-top-travellers
1517-find-users-with-valid-e-mails
1527-patients-with-a-condition
1890-the-latest-login-in-2020

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0128-longest-consecutive-sequence
0141-linked-list-cycle
0169-majority-element
0202-happy-number
0217-contains-duplicate
0219-contains-duplicate-ii
0242-valid-anagram
0290-word-pattern
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0383-ransom-note
0387-first-unique-character-in-a-string
0409-longest-palindrome
0442-find-all-duplicates-in-an-array
0448-find-all-numbers-disappeared-in-an-array
0560-subarray-sum-equals-k
0771-jewels-and-stones
0804-unique-morse-code-words
0819-most-common-word
0961-n-repeated-element-in-size-2n-array
1189-maximum-number-of-balloons
1346-check-if-n-and-its-double-exist
1358-number-of-substrings-containing-all-three-characters
1512-number-of-good-pairs
1813-maximum-erasure-value
2053-check-if-all-characters-have-equal-number-of-occurrences
2215-find-the-difference-of-two-arrays
2870-minimum-number-of-operations-to-make-array-empty
2965-find-missing-and-repeated-values
3289-the-two-sneaky-numbers-of-digitville
3568-minimum-moves-to-clean-the-classroom
3718-smallest-missing-multiple-of-k
3731-find-missing-elements
3788-maximum-unique-subarray-sum-after-deletion
3872-find-most-frequent-vowel-and-consonant

Sorting

0015-3sum
0088-merge-sorted-array
0148-sort-list
0169-majority-element
0179-largest-number
0217-contains-duplicate
0242-valid-anagram
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0378-kth-smallest-element-in-a-sorted-matrix
0414-third-maximum-number
0442-find-all-duplicates-in-an-array
0455-assign-cookies
0561-array-partition
0611-valid-triangle-number
0628-maximum-product-of-three-numbers
0976-largest-perimeter-triangle
0977-squares-of-a-sorted-array
1137-height-checker
1200-minimum-absolute-difference
1346-check-if-n-and-its-double-exist
1877-minimize-maximum-pair-sum-in-array
2112-minimum-difference-between-highest-and-lowest-of-k-scores
2144-minimum-cost-of-buying-candies-with-discount
2164-sort-even-and-odd-indices-independently
3010-divide-an-array-into-subarrays-with-minimum-cost-i
3321-type-of-triangle
3731-find-missing-elements
3867-sum-of-gcd-of-formed-pairs

Dynamic Programming

0005-longest-palindromic-substring
0042-trapping-rain-water
0053-maximum-subarray
0064-minimum-path-sum
0070-climbing-stairs
0118-pascals-triangle
0121-best-time-to-buy-and-sell-stock
0338-counting-bits
0396-rotate-function
0746-min-cost-climbing-stairs
0788-rotated-digits
0877-stone-game
1013-fibonacci-number
1025-divisor-game
1137-n-th-tribonacci-number
1700-minimum-time-to-make-rope-colorful

Sliding Window

0003-longest-substring-without-repeating-characters
0219-contains-duplicate-ii
0643-maximum-average-subarray-i
1358-number-of-substrings-containing-all-three-characters
1813-maximum-erasure-value
2112-minimum-difference-between-highest-and-lowest-of-k-scores

Two Pointers

0005-longest-palindromic-substring
0015-3sum
0019-remove-nth-node-from-end-of-list
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0042-trapping-rain-water
0061-rotate-list
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0148-sort-list
0151-reverse-words-in-a-string
0165-compare-version-numbers
0189-rotate-array
0202-happy-number
0283-move-zeroes
0287-find-the-duplicate-number
0344-reverse-string
0345-reverse-vowels-of-a-string
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0455-assign-cookies
0541-reverse-string-ii
0611-valid-triangle-number
0876-middle-of-the-linked-list
0977-squares-of-a-sorted-array
1346-check-if-n-and-its-double-exist
1877-minimize-maximum-pair-sum-in-array
1894-merge-strings-alternately
2000-reverse-prefix-of-word
2460-apply-operations-to-an-array
3867-sum-of-gcd-of-formed-pairs

Bit Manipulation

0029-divide-two-integers
0078-subsets
0136-single-number
0190-reverse-bits
0191-number-of-1-bits
0222-count-complete-tree-nodes
0231-power-of-two
0287-find-the-duplicate-number
0338-counting-bits
0342-power-of-four
0371-sum-of-two-integers
0461-hamming-distance
1404-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
3370-smallest-number-with-all-set-bits
3568-minimum-moves-to-clean-the-classroom

Greedy

0135-candy
0179-largest-number
0409-longest-palindrome
0455-assign-cookies
0561-array-partition
0611-valid-triangle-number
0976-largest-perimeter-triangle
1700-minimum-time-to-make-rope-colorful
1877-minimize-maximum-pair-sum-in-array
1927-sum-game
2144-minimum-cost-of-buying-candies-with-discount
2870-minimum-number-of-operations-to-make-array-empty
3788-maximum-unique-subarray-sum-after-deletion

Simulation

0054-spiral-matrix
0258-add-digits
0412-fizz-buzz
0498-diagonal-traverse
0566-reshape-the-matrix
0657-robot-return-to-origin
0682-baseball-game
0867-transpose-matrix
1404-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1642-water-bottles
1929-concatenation-of-array
2169-count-operations-to-obtain-zero
2177-find-three-consecutive-integers-that-sum-to-a-given-number
2390-removing-stars-from-a-string
2460-apply-operations-to-an-array
2553-separate-the-digits-in-an-array
3069-distribute-elements-into-two-arrays-i
3320-maximum-number-of-operations-with-the-same-score-i
3498-reverse-degree-of-a-string
3612-process-string-with-special-operations-i
3614-process-string-with-special-operations-ii
3701-compute-alternating-sum
3790-fruits-into-baskets-ii
3867-sum-of-gcd-of-formed-pairs

Number Theory

0204-count-primes
0258-add-digits
1952-three-divisors
2427-number-of-common-factors
2614-prime-in-diagonal
3115-maximum-prime-difference
3658-gcd-of-odd-and-even-sums
3867-sum-of-gcd-of-formed-pairs

Matrix

0048-rotate-image
0054-spiral-matrix
0064-minimum-path-sum
0074-search-a-2d-matrix
0378-kth-smallest-element-in-a-sorted-matrix
0498-diagonal-traverse
0566-reshape-the-matrix
0867-transpose-matrix
1351-count-negative-numbers-in-a-sorted-matrix
1582-special-positions-in-a-binary-matrix
1886-determine-whether-matrix-can-be-obtained-by-rotation
2614-prime-in-diagonal
2965-find-missing-and-repeated-values
3142-check-if-grid-satisfies-conditions
3568-minimum-moves-to-clean-the-classroom

Segment Tree

3790-fruits-into-baskets-ii

Ordered Set

3790-fruits-into-baskets-ii

Trie

0014-longest-common-prefix

Divide and Conquer

0053-maximum-subarray
0108-convert-sorted-array-to-binary-search-tree
0148-sort-list
0169-majority-element
0190-reverse-bits
0191-number-of-1-bits
0347-top-k-frequent-elements

Counting

0169-majority-element
0347-top-k-frequent-elements
0383-ransom-note
0387-first-unique-character-in-a-string
0819-most-common-word
1189-maximum-number-of-balloons
1512-number-of-good-pairs
2053-check-if-all-characters-have-equal-number-of-occurrences
2870-minimum-number-of-operations-to-make-array-empty
3872-find-most-frequent-vowel-and-consonant

Memoization

0070-climbing-stairs
1013-fibonacci-number
1137-n-th-tribonacci-number

Stack

0020-valid-parentheses
0042-trapping-rain-water
0094-binary-tree-inorder-traversal
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0394-decode-string
0682-baseball-game
2000-reverse-prefix-of-word
2390-removing-stars-from-a-string

Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0108-convert-sorted-array-to-binary-search-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0222-count-complete-tree-nodes
0404-sum-of-left-leaves
0671-second-minimum-node-in-a-binary-tree
0938-range-sum-of-bst
2265-count-nodes-equal-to-average-of-subtree

Depth-First Search

0094-binary-tree-inorder-traversal
0100-same-tree
0104-maximum-depth-of-binary-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0404-sum-of-left-leaves
0671-second-minimum-node-in-a-binary-tree
0938-range-sum-of-bst
2265-count-nodes-equal-to-average-of-subtree

Breadth-First Search

0100-same-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0112-path-sum
0404-sum-of-left-leaves
3568-minimum-moves-to-clean-the-classroom

Binary Tree

0094-binary-tree-inorder-traversal
0100-same-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0108-convert-sorted-array-to-binary-search-tree
0112-path-sum
0144-binary-tree-preorder-traversal
0145-binary-tree-postorder-traversal
0222-count-complete-tree-nodes
0404-sum-of-left-leaves
0671-second-minimum-node-in-a-binary-tree
0938-range-sum-of-bst
2265-count-nodes-equal-to-average-of-subtree

Counting Sort

0561-array-partition
1137-height-checker

Queue

0387-first-unique-character-in-a-string

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
1408-string-matching-in-an-array
3407-substring-matching-pattern

Prefix Sum

0560-subarray-sum-equals-k
1480-running-sum-of-1d-array
1732-find-the-highest-altitude
3432-count-partitions-with-even-sum-difference

Enumeration

0204-count-primes
1925-count-square-sum-triples
1952-three-divisors
2427-number-of-common-factors
3010-divide-an-array-into-subarrays-with-minimum-cost-i
3345-smallest-divisible-digit-product-i

Interactive

0278-first-bad-version

Brainteaser

0292-nim-game
1025-divisor-game
3227-vowels-game-in-a-string

Game Theory

0292-nim-game
0877-stone-game
1025-divisor-game
1927-sum-game
3227-vowels-game-in-a-string

Backtracking

0039-combination-sum
0078-subsets

Monotonic Stack

0042-trapping-rain-water

Heap (Priority Queue)

0347-top-k-frequent-elements
0378-kth-smallest-element-in-a-sorted-matrix

Bucket Sort

0347-top-k-frequent-elements

Quickselect

0347-top-k-frequent-elements

Binary Search Tree

0108-convert-sorted-array-to-binary-search-tree
0938-range-sum-of-bst

Merge Sort

0148-sort-list

Geometry

0812-largest-triangle-area
0836-rectangle-overlap
1401-circle-and-rectangle-overlapping

Union-Find

0128-longest-consecutive-sequence

Manacher

0005-longest-palindromic-substring