Leetcode-solutions

A collection of LeetCode questions to ace the coding interview!

LeetCode Topics

Array

0001-two-sum
0018-4sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0036-valid-sudoku
0037-sudoku-solver
0041-first-missing-positive
0042-trapping-rain-water
0045-jump-game-ii
0049-group-anagrams
0053-maximum-subarray
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0081-search-in-rotated-sorted-array-ii
0085-maximal-rectangle
0088-merge-sorted-array
0090-subsets-ii
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0118-pascals-triangle
0119-pascals-triangle-ii
0122-best-time-to-buy-and-sell-stock-ii
0128-longest-consecutive-sequence
0134-gas-station
0135-candy
0139-word-break
0140-word-break-ii
0179-largest-number
0321-create-maximum-number
0324-wiggle-sort-ii
0330-patching-array
0334-increasing-triplet-subsequence
0376-wiggle-subsequence

Hash Table

0001-two-sum
0017-letter-combinations-of-a-phone-number
0030-substring-with-concatenation-of-all-words
0036-valid-sudoku
0037-sudoku-solver
0041-first-missing-positive
0049-group-anagrams
0073-set-matrix-zeroes
0076-minimum-window-substring
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0126-word-ladder-ii
0127-word-ladder
0128-longest-consecutive-sequence
0133-clone-graph
0138-copy-list-with-random-pointer
0139-word-break
0140-word-break-ii
0141-linked-list-cycle
0142-linked-list-cycle-ii
0187-repeated-dna-sequences
0202-happy-number

String

0006-zigzag-conversion
0017-letter-combinations-of-a-phone-number
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0030-substring-with-concatenation-of-all-words
0044-wildcard-matching
0049-group-anagrams
0072-edit-distance
0076-minimum-window-substring
0087-scramble-string
0091-decode-ways
0093-restore-ip-addresses
0097-interleaving-string
0115-distinct-subsequences
0126-word-ladder-ii
0127-word-ladder
0139-word-break
0140-word-break-ii
0179-largest-number
0187-repeated-dna-sequences
0316-remove-duplicate-letters
0402-remove-k-digits

Two Pointers

0018-4sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0031-next-permutation
0042-trapping-rain-water
0086-partition-list
0088-merge-sorted-array
0141-linked-list-cycle
0142-linked-list-cycle-ii
0202-happy-number
0321-create-maximum-number

Sorting

0018-4sum
0049-group-anagrams
0088-merge-sorted-array
0179-largest-number
0324-wiggle-sort-ii

Dynamic Programming

0022-generate-parentheses
0042-trapping-rain-water
0044-wildcard-matching
0045-jump-game-ii
0053-maximum-subarray
0062-unique-paths
0063-unique-paths-ii
0064-minimum-path-sum
0070-climbing-stairs
0072-edit-distance
0085-maximal-rectangle
0087-scramble-string
0091-decode-ways
0095-unique-binary-search-trees-ii
0096-unique-binary-search-trees
0097-interleaving-string
0115-distinct-subsequences
0118-pascals-triangle
0119-pascals-triangle-ii
0122-best-time-to-buy-and-sell-stock-ii
0139-word-break
0140-word-break-ii
0376-wiggle-subsequence
0397-integer-replacement

Backtracking

0017-letter-combinations-of-a-phone-number
0022-generate-parentheses
0037-sudoku-solver
0089-gray-code
0090-subsets-ii
0093-restore-ip-addresses
0095-unique-binary-search-trees-ii
0126-word-ladder-ii
0140-word-break-ii

Linked List

0023-merge-k-sorted-lists
0024-swap-nodes-in-pairs
0025-reverse-nodes-in-k-group
0083-remove-duplicates-from-sorted-list
0086-partition-list
0092-reverse-linked-list-ii
0109-convert-sorted-list-to-binary-search-tree
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii
0138-copy-list-with-random-pointer
0141-linked-list-cycle
0142-linked-list-cycle-ii

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
0109-convert-sorted-list-to-binary-search-tree
0324-wiggle-sort-ii

Heap (Priority Queue)

0023-merge-k-sorted-lists

Merge Sort

0023-merge-k-sorted-lists

Stack

0042-trapping-rain-water
0085-maximal-rectangle
0094-binary-tree-inorder-traversal
0316-remove-duplicate-letters
0321-create-maximum-number
0402-remove-k-digits

Monotonic Stack

0042-trapping-rain-water
0085-maximal-rectangle
0316-remove-duplicate-letters
0321-create-maximum-number
0402-remove-k-digits

Greedy

0044-wildcard-matching
0045-jump-game-ii
0122-best-time-to-buy-and-sell-stock-ii
0134-gas-station
0135-candy
0179-largest-number
0316-remove-duplicate-letters
0321-create-maximum-number
0324-wiggle-sort-ii
0330-patching-array
0334-increasing-triplet-subsequence
0376-wiggle-subsequence
0397-integer-replacement
0402-remove-k-digits

Recursion

0024-swap-nodes-in-pairs
0025-reverse-nodes-in-k-group
0044-wildcard-matching

Math

0029-divide-two-integers
0062-unique-paths
0070-climbing-stairs
0089-gray-code
0096-unique-binary-search-trees
0202-happy-number

Combinatorics

0062-unique-paths

Matrix

0036-valid-sudoku
0037-sudoku-solver
0063-unique-paths-ii
0064-minimum-path-sum
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0085-maximal-rectangle

Memoization

0070-climbing-stairs
0139-word-break
0140-word-break-ii
0397-integer-replacement

Sliding Window

0030-substring-with-concatenation-of-all-words
0076-minimum-window-substring
0187-repeated-dna-sequences

Tree

0094-binary-tree-inorder-traversal
0095-unique-binary-search-trees-ii
0096-unique-binary-search-trees
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0107-binary-tree-level-order-traversal-ii
0108-convert-sorted-array-to-binary-search-tree
0109-convert-sorted-list-to-binary-search-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii

Binary Tree

0094-binary-tree-inorder-traversal
0095-unique-binary-search-trees-ii
0096-unique-binary-search-trees
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0107-binary-tree-level-order-traversal-ii
0108-convert-sorted-array-to-binary-search-tree
0109-convert-sorted-list-to-binary-search-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii

Breadth-First Search

0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0107-binary-tree-level-order-traversal-ii
0111-minimum-depth-of-binary-tree
0112-path-sum
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii
0126-word-ladder-ii
0127-word-ladder
0133-clone-graph

Union-Find

0128-longest-consecutive-sequence

Depth-First Search

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0116-populating-next-right-pointers-in-each-node
0117-populating-next-right-pointers-in-each-node-ii
0133-clone-graph

Graph Theory

0133-clone-graph

Trie

0139-word-break
0140-word-break-ii

Quickselect

0324-wiggle-sort-ii

Bit Manipulation

0029-divide-two-integers
0089-gray-code
0090-subsets-ii
0187-repeated-dna-sequences
0397-integer-replacement

Binary Search Tree

0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0074-search-a-2d-matrix
0081-search-in-rotated-sorted-array-ii
0095-unique-binary-search-trees-ii
0096-unique-binary-search-trees
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0108-convert-sorted-array-to-binary-search-tree
0109-convert-sorted-list-to-binary-search-tree

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string

Rolling Hash

0187-repeated-dna-sequences

Hash Function

0187-repeated-dna-sequences