LeetCode

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

LeetCode Topics

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
0086-partition-list
0092-reverse-linked-list-ii
0114-flatten-binary-tree-to-linked-list
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0148-sort-list
0160-intersection-of-two-linked-lists
0206-reverse-linked-list
0234-palindrome-linked-list
0237-delete-node-in-a-linked-list
0328-odd-even-linked-list
0528-swapping-nodes-in-a-linked-list
0908-middle-of-the-linked-list
1411-convert-binary-number-in-a-linked-list-to-integer
2216-delete-the-middle-node-of-a-linked-list
2573-remove-nodes-from-linked-list

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0024-swap-nodes-in-pairs
0044-wildcard-matching
0206-reverse-linked-list
0231-power-of-two
0234-palindrome-linked-list
1013-fibonacci-number
1197-parsing-a-boolean-expression
2573-remove-nodes-from-linked-list

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0031-next-permutation
0042-trapping-rain-water
0061-rotate-list
0075-sort-colors
0082-remove-duplicates-from-sorted-list-ii
0086-partition-list
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0142-linked-list-cycle-ii
0148-sort-list
0160-intersection-of-two-linked-lists
0234-palindrome-linked-list
0283-move-zeroes
0344-reverse-string
0349-intersection-of-two-arrays
0392-is-subsequence
0528-swapping-nodes-in-a-linked-list
0696-count-binary-substrings
0811-number-of-subarrays-with-bounded-maximum
0908-middle-of-the-linked-list
2216-delete-the-middle-node-of-a-linked-list
2271-rearrange-array-elements-by-sign

Hash Table

0001-two-sum
0049-group-anagrams
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0128-longest-consecutive-sequence
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii
0149-max-points-on-a-line
0160-intersection-of-two-linked-lists
0242-valid-anagram
0268-missing-number
0349-intersection-of-two-arrays
0387-first-unique-character-in-a-string
0523-continuous-subarray-sum
0525-contiguous-array
0554-brick-wall
0560-subarray-sum-equals-k
0782-jewels-and-stones
0905-length-of-longest-fibonacci-subsequence
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0966-binary-subarrays-with-sum
1044-find-common-characters
1160-letter-tile-possibilities
1364-tuple-with-same-product
1387-find-elements-in-a-contaminated-binary-tree
1915-check-if-one-string-swap-can-make-strings-equal
2107-find-unique-binary-string
2119-minimum-number-of-operations-to-make-array-continuous
2237-longest-palindrome-by-concatenating-two-letter-words
2434-design-a-number-container-system
3434-find-the-number-of-distinct-colors-among-the-balls
3914-check-if-any-element-has-prime-frequency

Stack

0020-valid-parentheses
0042-trapping-rain-water
0071-simplify-path
0114-flatten-binary-tree-to-linked-list
0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0957-minimum-add-to-make-parentheses-valid
1078-remove-outermost-parentheses
1197-parsing-a-boolean-expression
1737-maximum-nesting-depth-of-the-parentheses
1756-minimum-deletions-to-make-string-balanced
2021-remove-all-occurrences-of-a-substring
2456-construct-smallest-number-from-di-string
2573-remove-nodes-from-linked-list
3447-clear-digits

Math

0002-add-two-numbers
0007-reverse-integer
0069-sqrtx
0070-climbing-stairs
0149-max-points-on-a-line
0231-power-of-two
0268-missing-number
0367-valid-perfect-square
0523-continuous-subarray-sum
1013-fibonacci-number
1086-divisor-game
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
2106-find-greatest-common-divisor-of-array
2802-find-the-punishment-number-of-an-integer
3704-count-partitions-with-even-sum-difference
3768-check-if-digits-are-equal-in-string-after-operations-i
3914-check-if-any-element-has-prime-frequency

Array

0001-two-sum
0011-container-with-most-water
0015-3sum
0016-3sum-closest
0026-remove-duplicates-from-sorted-array
0031-next-permutation
0033-search-in-rotated-sorted-array
0042-trapping-rain-water
0049-group-anagrams
0051-n-queens
0053-maximum-subarray
0064-minimum-path-sum
0075-sort-colors
0088-merge-sorted-array
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0120-triangle
0128-longest-consecutive-sequence
0136-single-number
0149-max-points-on-a-line
0198-house-robber
0209-minimum-size-subarray-sum
0213-house-robber-ii
0268-missing-number
0283-move-zeroes
0300-longest-increasing-subsequence
0303-range-sum-query-immutable
0322-coin-change
0349-intersection-of-two-arrays
0485-max-consecutive-ones
0494-target-sum
0518-coin-change-ii
0523-continuous-subarray-sum
0525-contiguous-array
0554-brick-wall
0560-subarray-sum-equals-k
0792-binary-search
0811-number-of-subarrays-with-bounded-maximum
0905-length-of-longest-fibonacci-subsequence
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0948-sort-an-array
0966-binary-subarrays-with-sum
1025-minimum-cost-for-tickets
1044-find-common-characters
1364-tuple-with-same-product
1477-product-of-the-last-k-numbers
1631-number-of-sub-arrays-with-odd-sum
1819-construct-the-lexicographically-largest-valid-sequence
1849-maximum-absolute-sum-of-any-subarray
1878-check-if-array-is-sorted-and-rotated
1927-maximum-ascending-subarray-sum
2106-find-greatest-common-divisor-of-array
2107-find-unique-binary-string
2119-minimum-number-of-operations-to-make-array-continuous
2237-longest-palindrome-by-concatenating-two-letter-words
2271-rearrange-array-elements-by-sign
2564-most-profitable-path-in-a-tree
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
3704-count-partitions-with-even-sum-difference
3914-check-if-any-element-has-prime-frequency

Prefix Sum

0209-minimum-size-subarray-sum
0303-range-sum-query-immutable
0523-continuous-subarray-sum
0525-contiguous-array
0560-subarray-sum-equals-k
0966-binary-subarrays-with-sum
1477-product-of-the-last-k-numbers
1631-number-of-sub-arrays-with-odd-sum
3704-count-partitions-with-even-sum-difference

Monotonic Stack

0042-trapping-rain-water
2573-remove-nodes-from-linked-list

String

0005-longest-palindromic-substring
0020-valid-parentheses
0044-wildcard-matching
0049-group-anagrams
0071-simplify-path
0072-edit-distance
0125-valid-palindrome
0131-palindrome-partitioning
0242-valid-anagram
0344-reverse-string
0387-first-unique-character-in-a-string
0392-is-subsequence
0516-longest-palindromic-subsequence
0583-delete-operation-for-two-strings
0696-count-binary-substrings
0782-jewels-and-stones
0957-minimum-add-to-make-parentheses-valid
1044-find-common-characters
1078-remove-outermost-parentheses
1093-recover-a-tree-from-preorder-traversal
1160-letter-tile-possibilities
1170-shortest-common-supersequence
1197-parsing-a-boolean-expression
1437-minimum-insertion-steps-to-make-a-string-palindrome
1516-the-k-th-lexicographical-string-of-all-happy-strings-of-length-n
1737-maximum-nesting-depth-of-the-parentheses
1756-minimum-deletions-to-make-string-balanced
1915-check-if-one-string-swap-can-make-strings-equal
2021-remove-all-occurrences-of-a-substring
2107-find-unique-binary-string
2237-longest-palindrome-by-concatenating-two-letter-words
2456-construct-smallest-number-from-di-string
3447-clear-digits
3768-check-if-digits-are-equal-in-string-after-operations-i

Design

0155-min-stack
0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0303-range-sum-query-immutable
1387-find-elements-in-a-contaminated-binary-tree
1477-product-of-the-last-k-numbers
2434-design-a-number-container-system

Queue

0225-implement-stack-using-queues
0232-implement-queue-using-stacks
0387-first-unique-character-in-a-string

Counting

0387-first-unique-character-in-a-string
1160-letter-tile-possibilities
1364-tuple-with-same-product
1915-check-if-one-string-swap-can-make-strings-equal
2237-longest-palindrome-by-concatenating-two-letter-words
3914-check-if-any-element-has-prime-frequency

Simulation

2021-remove-all-occurrences-of-a-substring
2271-rearrange-array-elements-by-sign
3332-minimum-operations-to-exceed-threshold-value-ii
3434-find-the-number-of-distinct-colors-among-the-balls
3447-clear-digits
3768-check-if-digits-are-equal-in-string-after-operations-i

Heap (Priority Queue)

0023-merge-k-sorted-lists
0948-sort-an-array
2434-design-a-number-container-system
3332-minimum-operations-to-exceed-threshold-value-ii

Ordered Set

2434-design-a-number-container-system

Sorting

0015-3sum
0016-3sum-closest
0049-group-anagrams
0075-sort-colors
0088-merge-sorted-array
0148-sort-list
0242-valid-anagram
0268-missing-number
0349-intersection-of-two-arrays
0948-sort-an-array

Data Stream

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

Backtracking

0051-n-queens
0131-palindrome-partitioning
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
2107-find-unique-binary-string
2456-construct-smallest-number-from-di-string
2802-find-the-punishment-number-of-an-integer

Greedy

0011-container-with-most-water
0044-wildcard-matching
0957-minimum-add-to-make-parentheses-valid
2237-longest-palindrome-by-concatenating-two-letter-words
2456-construct-smallest-number-from-di-string

Union Find

0128-longest-consecutive-sequence

Tree

0101-symmetric-tree
0103-binary-tree-zigzag-level-order-traversal
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0114-flatten-binary-tree-to-linked-list
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree
2564-most-profitable-path-in-a-tree

Depth-First Search

0101-symmetric-tree
0114-flatten-binary-tree-to-linked-list
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree
2564-most-profitable-path-in-a-tree

Breadth-First Search

0101-symmetric-tree
0103-binary-tree-zigzag-level-order-traversal
0322-coin-change
1387-find-elements-in-a-contaminated-binary-tree
2564-most-profitable-path-in-a-tree

Binary Tree

0101-symmetric-tree
0103-binary-tree-zigzag-level-order-traversal
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0114-flatten-binary-tree-to-linked-list
0925-construct-binary-tree-from-preorder-and-postorder-traversal
1093-recover-a-tree-from-preorder-traversal
1387-find-elements-in-a-contaminated-binary-tree

Divide and Conquer

0023-merge-k-sorted-lists
0053-maximum-subarray
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0148-sort-list
0925-construct-binary-tree-from-preorder-and-postorder-traversal
0948-sort-an-array

Combinatorics

3768-check-if-digits-are-equal-in-string-after-operations-i

Number Theory

2106-find-greatest-common-divisor-of-array
3768-check-if-digits-are-equal-in-string-after-operations-i
3914-check-if-any-element-has-prime-frequency

Graph

2564-most-profitable-path-in-a-tree

Dynamic Programming

0005-longest-palindromic-substring
0042-trapping-rain-water
0044-wildcard-matching
0053-maximum-subarray
0064-minimum-path-sum
0070-climbing-stairs
0072-edit-distance
0120-triangle
0131-palindrome-partitioning
0198-house-robber
0213-house-robber-ii
0300-longest-increasing-subsequence
0322-coin-change
0338-counting-bits
0392-is-subsequence
0494-target-sum
0516-longest-palindromic-subsequence
0518-coin-change-ii
0583-delete-operation-for-two-strings
0905-length-of-longest-fibonacci-subsequence
1013-fibonacci-number
1025-minimum-cost-for-tickets
1086-divisor-game
1170-shortest-common-supersequence
1437-minimum-insertion-steps-to-make-a-string-palindrome
1631-number-of-sub-arrays-with-odd-sum
1756-minimum-deletions-to-make-string-balanced
1849-maximum-absolute-sum-of-any-subarray

Binary Search

0033-search-in-rotated-sorted-array
0069-sqrtx
0209-minimum-size-subarray-sum
0268-missing-number
0300-longest-increasing-subsequence
0349-intersection-of-two-arrays
0367-valid-perfect-square
0792-binary-search
2119-minimum-number-of-operations-to-make-array-continuous

Sliding Window

0209-minimum-size-subarray-sum
0966-binary-subarrays-with-sum
2119-minimum-number-of-operations-to-make-array-continuous

Bit Manipulation

0136-single-number
0231-power-of-two
0268-missing-number
0338-counting-bits

Memoization

0070-climbing-stairs
1013-fibonacci-number

Binary Search Tree

0108-convert-sorted-array-to-binary-search-tree

Geometry

0149-max-points-on-a-line

Merge Sort

0023-merge-k-sorted-lists
0148-sort-list
0948-sort-an-array

Brainteaser

1086-divisor-game

Game Theory

1086-divisor-game

Matrix

0064-minimum-path-sum

Bucket Sort

0948-sort-an-array

Radix Sort

0948-sort-an-array

Counting Sort

0948-sort-an-array