LEETCODE

LeetCode Topics

Array

0026-remove-duplicates-from-sorted-array
0027-remove-element
0035-search-insert-position
0041-first-missing-positive
0066-plus-one
0080-remove-duplicates-from-sorted-array-ii
0088-merge-sorted-array
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0118-pascals-triangle
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0130-surrounded-regions
0136-single-number
0150-evaluate-reverse-polish-notation
0169-majority-element
0189-rotate-array
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0283-move-zeroes
0448-find-all-numbers-disappeared-in-an-array
0496-next-greater-element-i
0542-01-matrix
0724-find-pivot-index
0733-flood-fill
0878-shifting-letters
0965-unique-email-addresses
1019-squares-of-a-sorted-array
1036-rotting-oranges
1073-number-of-enclaves
1127-last-stone-weight
1364-tuple-with-same-product
1477-product-of-the-last-k-numbers
1524-string-matching-in-an-array
1603-running-sum-of-1d-array
1878-check-if-array-is-sorted-and-rotated
1927-maximum-ascending-subarray-sum
2358-number-of-ways-to-split-array
2448-count-number-of-bad-pairs
2465-shifting-letters-ii
2473-max-sum-of-a-pair-with-equal-sum-of-digits
2691-count-vowel-strings-in-ranges
3309-count-prefix-and-suffix-pairs-i
3332-minimum-operations-to-exceed-threshold-value-ii
3372-longest-strictly-increasing-or-strictly-decreasing-subarray
3434-find-the-number-of-distinct-colors-among-the-balls

Binary Search

0035-search-insert-position
0222-count-complete-tree-nodes
0441-arranging-coins

Two Pointers

0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0080-remove-duplicates-from-sorted-array-ii
0086-partition-list
0088-merge-sorted-array
0125-valid-palindrome
0148-sort-list
0151-reverse-words-in-a-string
0160-intersection-of-two-linked-lists
0189-rotate-array
0234-palindrome-linked-list
0283-move-zeroes
0653-two-sum-iv-input-is-a-bst
0908-middle-of-the-linked-list
1019-squares-of-a-sorted-array
2216-delete-the-middle-node-of-a-linked-list

Heap (Priority Queue)

0215-kth-largest-element-in-an-array
0789-kth-largest-element-in-a-stream
1127-last-stone-weight
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

Math

0002-add-two-numbers
0012-integer-to-roman
0066-plus-one
0150-evaluate-reverse-polish-notation
0189-rotate-array
0263-ugly-number
0415-add-strings
0441-arranging-coins
1477-product-of-the-last-k-numbers
2448-count-number-of-bad-pairs

String

0008-string-to-integer-atoi
0012-integer-to-roman
0020-valid-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0058-length-of-last-word
0125-valid-palindrome
0127-word-ladder
0151-reverse-words-in-a-string
0205-isomorphic-strings
0257-binary-tree-paths
0297-serialize-and-deserialize-binary-tree
0402-remove-k-digits
0415-add-strings
0606-construct-string-from-binary-tree
0878-shifting-letters
0965-unique-email-addresses
1128-remove-all-adjacent-duplicates-in-string
1297-maximum-number-of-balloons
1320-remove-all-adjacent-duplicates-in-string-ii
1524-string-matching-in-an-array
1537-maximum-score-after-splitting-a-string
1667-find-kth-bit-in-nth-binary-string
1915-check-if-one-string-swap-can-make-strings-equal
2021-remove-all-occurrences-of-a-substring
2059-unique-length-3-palindromic-subsequences
2465-shifting-letters-ii
2691-count-vowel-strings-in-ranges
3309-count-prefix-and-suffix-pairs-i
3447-clear-digits

Hash Table

0012-integer-to-roman
0041-first-missing-positive
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0127-word-ladder
0160-intersection-of-two-linked-lists
0169-majority-element
0205-isomorphic-strings
0217-contains-duplicate
0448-find-all-numbers-disappeared-in-an-array
0496-next-greater-element-i
0653-two-sum-iv-input-is-a-bst
0965-unique-email-addresses
1297-maximum-number-of-balloons
1364-tuple-with-same-product
1915-check-if-one-string-swap-can-make-strings-equal
2059-unique-length-3-palindromic-subsequences
2434-design-a-number-container-system
2448-count-number-of-bad-pairs
2473-max-sum-of-a-pair-with-equal-sum-of-digits
3434-find-the-number-of-distinct-colors-among-the-balls

Divide and Conquer

0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0148-sort-list
0169-majority-element
0191-number-of-1-bits
0215-kth-largest-element-in-an-array

Bit Manipulation

0136-single-number
0191-number-of-1-bits
0222-count-complete-tree-nodes
2059-unique-length-3-palindromic-subsequences
2323-minimum-bit-flips-to-convert-number

Sorting

0088-merge-sorted-array
0148-sort-list
0169-majority-element
0215-kth-largest-element-in-an-array
0217-contains-duplicate
1019-squares-of-a-sorted-array
2473-max-sum-of-a-pair-with-equal-sum-of-digits

Quickselect

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

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0025-reverse-nodes-in-k-group
0083-remove-duplicates-from-sorted-list
0086-partition-list
0148-sort-list
0160-intersection-of-two-linked-lists
0206-reverse-linked-list
0234-palindrome-linked-list
0908-middle-of-the-linked-list
2216-delete-the-middle-node-of-a-linked-list

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0572-subtree-of-another-tree
1524-string-matching-in-an-array
3309-count-prefix-and-suffix-pairs-i

Counting

0169-majority-element
1297-maximum-number-of-balloons
1364-tuple-with-same-product
1915-check-if-one-string-swap-can-make-strings-equal
2448-count-number-of-bad-pairs

Stack

0020-valid-parentheses
0094-binary-tree-inorder-traversal
0145-binary-tree-postorder-traversal
0150-evaluate-reverse-polish-notation
0155-min-stack
0225-implement-stack-using-queues
0234-palindrome-linked-list
0402-remove-k-digits
0496-next-greater-element-i
0933-increasing-order-search-tree
1128-remove-all-adjacent-duplicates-in-string
1320-remove-all-adjacent-duplicates-in-string-ii
2021-remove-all-occurrences-of-a-substring
3447-clear-digits

Design

0155-min-stack
0225-implement-stack-using-queues
0297-serialize-and-deserialize-binary-tree
0789-kth-largest-element-in-a-stream
1477-product-of-the-last-k-numbers
2434-design-a-number-container-system

Queue

0225-implement-stack-using-queues

Prefix Sum

0724-find-pivot-index
0878-shifting-letters
1477-product-of-the-last-k-numbers
1537-maximum-score-after-splitting-a-string
1603-running-sum-of-1d-array
2059-unique-length-3-palindromic-subsequences
2358-number-of-ways-to-split-array
2465-shifting-letters-ii
2691-count-vowel-strings-in-ranges

Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0112-path-sum
0129-sum-root-to-leaf-numbers
0145-binary-tree-postorder-traversal
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0257-binary-tree-paths
0297-serialize-and-deserialize-binary-tree
0404-sum-of-left-leaves
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0563-binary-tree-tilt
0572-subtree-of-another-tree
0606-construct-string-from-binary-tree
0617-merge-two-binary-trees
0637-average-of-levels-in-binary-tree
0653-two-sum-iv-input-is-a-bst
0671-second-minimum-node-in-a-binary-tree
0774-maximum-depth-of-n-ary-tree
0783-search-in-a-binary-search-tree
0789-kth-largest-element-in-a-stream
0904-leaf-similar-trees
0933-increasing-order-search-tree
0988-flip-equivalent-binary-trees
1035-cousins-in-binary-tree
1544-count-good-nodes-in-binary-tree
2384-root-equals-sum-of-children
2416-evaluate-boolean-binary-tree

Depth-First Search

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0112-path-sum
0129-sum-root-to-leaf-numbers
0130-surrounded-regions
0145-binary-tree-postorder-traversal
0199-binary-tree-right-side-view
0210-course-schedule-ii
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0257-binary-tree-paths
0297-serialize-and-deserialize-binary-tree
0404-sum-of-left-leaves
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0547-number-of-provinces
0563-binary-tree-tilt
0572-subtree-of-another-tree
0606-construct-string-from-binary-tree
0617-merge-two-binary-trees
0637-average-of-levels-in-binary-tree
0653-two-sum-iv-input-is-a-bst
0671-second-minimum-node-in-a-binary-tree
0733-flood-fill
0774-maximum-depth-of-n-ary-tree
0801-is-graph-bipartite
0904-leaf-similar-trees
0933-increasing-order-search-tree
0988-flip-equivalent-binary-trees
1035-cousins-in-binary-tree
1073-number-of-enclaves
1544-count-good-nodes-in-binary-tree
2416-evaluate-boolean-binary-tree

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0112-path-sum
0127-word-ladder
0130-surrounded-regions
0199-binary-tree-right-side-view
0210-course-schedule-ii
0226-invert-binary-tree
0297-serialize-and-deserialize-binary-tree
0404-sum-of-left-leaves
0530-minimum-absolute-difference-in-bst
0542-01-matrix
0547-number-of-provinces
0617-merge-two-binary-trees
0637-average-of-levels-in-binary-tree
0653-two-sum-iv-input-is-a-bst
0733-flood-fill
0774-maximum-depth-of-n-ary-tree
0801-is-graph-bipartite
1035-cousins-in-binary-tree
1036-rotting-oranges
1073-number-of-enclaves
1544-count-good-nodes-in-binary-tree

Binary Tree

0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0108-convert-sorted-array-to-binary-search-tree
0110-balanced-binary-tree
0112-path-sum
0129-sum-root-to-leaf-numbers
0145-binary-tree-postorder-traversal
0199-binary-tree-right-side-view
0222-count-complete-tree-nodes
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0257-binary-tree-paths
0297-serialize-and-deserialize-binary-tree
0404-sum-of-left-leaves
0530-minimum-absolute-difference-in-bst
0543-diameter-of-binary-tree
0563-binary-tree-tilt
0572-subtree-of-another-tree
0606-construct-string-from-binary-tree
0617-merge-two-binary-trees
0637-average-of-levels-in-binary-tree
0653-two-sum-iv-input-is-a-bst
0671-second-minimum-node-in-a-binary-tree
0783-search-in-a-binary-search-tree
0789-kth-largest-element-in-a-stream
0904-leaf-similar-trees
0933-increasing-order-search-tree
0988-flip-equivalent-binary-trees
1035-cousins-in-binary-tree
1544-count-good-nodes-in-binary-tree
2384-root-equals-sum-of-children
2416-evaluate-boolean-binary-tree

Binary Search Tree

0098-validate-binary-search-tree
0108-convert-sorted-array-to-binary-search-tree
0230-kth-smallest-element-in-a-bst
0235-lowest-common-ancestor-of-a-binary-search-tree
0530-minimum-absolute-difference-in-bst
0653-two-sum-iv-input-is-a-bst
0783-search-in-a-binary-search-tree
0789-kth-largest-element-in-a-stream
0933-increasing-order-search-tree

Dynamic Programming

0118-pascals-triangle
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0542-01-matrix

Hash Function

0572-subtree-of-another-tree
3309-count-prefix-and-suffix-pairs-i

Simulation

0415-add-strings
1667-find-kth-bit-in-nth-binary-string
2021-remove-all-occurrences-of-a-substring
3332-minimum-operations-to-exceed-threshold-value-ii
3434-find-the-number-of-distinct-colors-among-the-balls
3447-clear-digits

Ordered Set

2434-design-a-number-container-system

Data Stream

0789-kth-largest-element-in-a-stream
1477-product-of-the-last-k-numbers

Backtracking

0257-binary-tree-paths

Trie

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

Rolling Hash

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

Union Find

0130-surrounded-regions
0547-number-of-provinces
0801-is-graph-bipartite
1073-number-of-enclaves

Graph

0210-course-schedule-ii
0547-number-of-provinces
0801-is-graph-bipartite

Matrix

0130-surrounded-regions
0542-01-matrix
0733-flood-fill
1036-rotting-oranges
1073-number-of-enclaves

Monotonic Stack

0402-remove-k-digits
0496-next-greater-element-i

Topological Sort

0210-course-schedule-ii

Greedy

0122-best-time-to-buy-and-sell-stock-ii
0402-remove-k-digits

Recursion

0002-add-two-numbers
0021-merge-two-sorted-lists
0025-reverse-nodes-in-k-group
0206-reverse-linked-list
0234-palindrome-linked-list
1667-find-kth-bit-in-nth-binary-string

Merge Sort

0148-sort-list