leetcode-solutions

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

LeetCode Topics

Array

0001-two-sum
0018-4sum
0066-plus-one
0085-maximal-rectangle
0137-single-number-ii
0200-number-of-islands
0219-contains-duplicate-ii
0312-burst-balloons
0321-create-maximum-number
0330-patching-array
0336-palindrome-pairs
0416-partition-equal-subset-sum
0421-maximum-xor-of-two-numbers-in-an-array
0494-target-sum
0643-maximum-average-subarray-i
0691-stickers-to-spell-word
0721-accounts-merge
0843-binary-trees-with-factors
0870-magic-squares-in-grid
0914-random-point-in-non-overlapping-rectangles
0954-maximum-sum-circular-subarray
0981-delete-columns-to-make-sorted
0992-delete-columns-to-make-sorted-ii
1000-delete-columns-to-make-sorted-iii
1001-n-repeated-element-in-size-2n-array
1232-sum-of-mutated-array-closest-to-target
1284-four-divisors
1305-number-of-visible-people-in-a-queue
1306-minimum-absolute-difference
1311-largest-magic-square
1331-path-with-maximum-gold
1395-minimum-time-visiting-all-points
1396-count-servers-that-communicate
1413-maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold
1458-sort-integers-by-the-number-of-1-bits
1476-count-negative-numbers-in-a-sorted-matrix
1533-display-table-of-food-orders-in-a-restaurant
1569-max-dot-product-of-two-subsequences
1831-ways-to-split-array-into-three-subarrays
1833-find-the-highest-altitude
1988-minimize-maximum-pair-sum-in-array
1990-get-biggest-three-rhombus-sums-in-a-grid
2042-maximum-product-difference-between-two-pairs
2058-concatenation-of-array
2089-maximum-matrix-sum
2107-find-unique-binary-string
2112-minimum-difference-between-highest-and-lowest-of-k-scores
2164-two-best-non-overlapping-events
2206-detonate-the-maximum-bombs
2233-number-of-smooth-descent-periods-of-a-stock
2430-number-of-excellent-pairs
2479-meeting-rooms-iii
2505-number-of-good-paths
3214-maximize-area-of-square-hole-in-grid
3235-minimum-cost-to-convert-string-i
3238-minimum-cost-to-convert-string-ii
3250-maximum-square-area-by-removing-fences-from-a-field
3260-divide-an-array-into-subarrays-with-minimum-cost-ii
3263-divide-an-array-into-subarrays-with-minimum-cost-i
3290-number-of-subarrays-that-match-a-pattern-ii
3325-find-the-largest-area-of-square-inside-two-rectangles
3334-apple-redistribution-into-boxes
3351-maximize-happiness-of-selected-children
3356-shortest-uncommon-substring-in-an-array
3404-minimum-number-of-operations-to-satisfy-conditions
3416-sum-of-digit-differences-of-all-pairs
3526-minimum-number-of-flips-to-make-binary-grid-palindromic-i
3605-construct-the-minimum-bitwise-array-i
3611-construct-the-minimum-bitwise-array-ii
3721-count-mentions-per-user
3763-separate-squares-i
3772-minimum-pair-removal-to-sort-array-ii
3773-minimum-pair-removal-to-sort-array-i
3775-separate-squares-ii
3819-count-covered-buildings
3854-maximum-profit-from-trading-stocks-with-discounts
3889-minimum-cost-path-with-teleportations
3892-best-time-to-buy-and-sell-stock-v
3934-coupon-code-validator
3941-number-of-integers-with-popcount-depth-equal-to-k-ii
3952-trionic-array-i
3956-trionic-array-ii
3980-best-time-to-buy-and-sell-stock-using-strategy
3986-maximum-path-score-in-a-grid
4061-minimum-swaps-to-avoid-forbidden-values
4154-maximum-bitwise-and-after-increment-operations

Hash Table

0001-two-sum
0219-contains-duplicate-ii
0336-palindrome-pairs
0395-longest-substring-with-at-least-k-repeating-characters
0421-maximum-xor-of-two-numbers-in-an-array
0424-longest-repeating-character-replacement
0691-stickers-to-spell-word
0721-accounts-merge
0757-pyramid-transition-matrix
0843-binary-trees-with-factors
0870-magic-squares-in-grid
0896-smallest-subtree-with-all-the-deepest-nodes
1001-n-repeated-element-in-size-2n-array
1460-number-of-substrings-containing-all-three-characters
1533-display-table-of-food-orders-in-a-restaurant
2053-check-if-all-characters-have-equal-number-of-occurrences
2107-find-unique-binary-string
2430-number-of-excellent-pairs
2479-meeting-rooms-iii
2505-number-of-good-paths
3250-maximum-square-area-by-removing-fences-from-a-field
3260-divide-an-array-into-subarrays-with-minimum-cost-ii
3267-find-longest-special-substring-that-occurs-thrice-i
3276-minimum-number-of-pushes-to-type-word-ii
3356-shortest-uncommon-substring-in-an-array
3416-sum-of-digit-differences-of-all-pairs
3754-maximum-manhattan-distance-after-k-changes
3772-minimum-pair-removal-to-sort-array-ii
3773-minimum-pair-removal-to-sort-array-i
3819-count-covered-buildings
3934-coupon-code-validator
4061-minimum-swaps-to-avoid-forbidden-values

String

0028-find-the-index-of-the-first-occurrence-in-a-string
0214-shortest-palindrome
0301-remove-invalid-parentheses
0336-palindrome-pairs
0394-decode-string
0395-longest-substring-with-at-least-k-repeating-characters
0424-longest-repeating-character-replacement
0481-magical-string
0514-freedom-trail
0691-stickers-to-spell-word
0712-minimum-ascii-delete-sum-for-two-strings
0721-accounts-merge
0757-pyramid-transition-matrix
0763-special-binary-string
0981-delete-columns-to-make-sorted
0992-delete-columns-to-make-sorted-ii
1000-delete-columns-to-make-sorted-iii
1298-reverse-substrings-between-each-pair-of-parentheses
1460-number-of-substrings-containing-all-three-characters
1508-longest-happy-prefix
1520-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1533-display-table-of-food-orders-in-a-restaurant
1756-minimum-deletions-to-make-string-balanced
1807-partitioning-into-minimum-number-of-deci-binary-numbers
2017-minimum-number-of-flips-to-make-the-binary-string-alternating
2053-check-if-all-characters-have-equal-number-of-occurrences
2107-find-unique-binary-string
2251-number-of-ways-to-divide-a-long-corridor
2576-minimum-penalty-for-a-shop
3235-minimum-cost-to-convert-string-i
3238-minimum-cost-to-convert-string-ii
3267-find-longest-special-substring-that-occurs-thrice-i
3276-minimum-number-of-pushes-to-type-word-ii
3356-shortest-uncommon-substring-in-an-array
3754-maximum-manhattan-distance-after-k-changes
3934-coupon-code-validator
3983-minimum-operations-to-equalize-binary-string
3999-minimum-operations-to-transform-string
4136-concatenate-non-zero-digits-and-multiply-by-sum-ii
4221-longest-almost-palindromic-substring

Dynamic Programming

0085-maximal-rectangle
0233-number-of-digit-one
0312-burst-balloons
0416-partition-equal-subset-sum
0494-target-sum
0514-freedom-trail
0691-stickers-to-spell-word
0712-minimum-ascii-delete-sum-for-two-strings
0843-binary-trees-with-factors
0863-sum-of-distances-in-tree
0954-maximum-sum-circular-subarray
1000-delete-columns-to-make-sorted-iii
1263-number-of-dice-rolls-with-target-sum
1527-number-of-ways-to-paint-n-3-grid
1569-max-dot-product-of-two-subsequences
1756-minimum-deletions-to-make-string-balanced
1996-number-of-ways-to-rearrange-sticks-with-k-sticks-visible
2017-minimum-number-of-flips-to-make-the-binary-string-alternating
2031-egg-drop-with-2-eggs-and-n-floors
2164-two-best-non-overlapping-events
2233-number-of-smooth-descent-periods-of-a-stock
2251-number-of-ways-to-divide-a-long-corridor
2710-minimum-operations-to-reduce-an-integer-to-0
3238-minimum-cost-to-convert-string-ii
3404-minimum-number-of-operations-to-satisfy-conditions
3406-find-all-possible-stable-binary-arrays-i
3407-find-all-possible-stable-binary-arrays-ii
3854-maximum-profit-from-trading-stocks-with-discounts
3889-minimum-cost-path-with-teleportations
3892-best-time-to-buy-and-sell-stock-v
3956-trionic-array-ii
3986-maximum-path-score-in-a-grid
4221-longest-almost-palindromic-substring

Backtracking

0089-gray-code
0301-remove-invalid-parentheses
0494-target-sum
0691-stickers-to-spell-word
0757-pyramid-transition-matrix
1331-path-with-maximum-gold
2107-find-unique-binary-string

Bit Manipulation

0089-gray-code
0137-single-number-ii
0421-maximum-xor-of-two-numbers-in-an-array
0691-stickers-to-spell-word
0757-pyramid-transition-matrix
0767-prime-number-of-set-bits-in-binary-representation
0795-k-th-symbol-in-grammar
1458-sort-integers-by-the-number-of-1-bits
1520-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1800-concatenation-of-consecutive-binary-numbers
2430-number-of-excellent-pairs
2710-minimum-operations-to-reduce-an-integer-to-0
3605-construct-the-minimum-bitwise-array-i
3611-construct-the-minimum-bitwise-array-ii
4154-maximum-bitwise-and-after-increment-operations

Memoization

0691-stickers-to-spell-word

Bitmask

0691-stickers-to-spell-word

Breadth-First Search

0200-number-of-islands
0301-remove-invalid-parentheses
0514-freedom-trail
0721-accounts-merge
0896-smallest-subtree-with-all-the-deepest-nodes
1116-maximum-level-sum-of-a-binary-tree
1396-count-servers-that-communicate
2206-detonate-the-maximum-bombs
2213-find-all-people-with-secret
3983-minimum-operations-to-equalize-binary-string

Sorting

0018-4sum
0721-accounts-merge
0763-special-binary-string
0843-binary-trees-with-factors
1232-sum-of-mutated-array-closest-to-target
1306-minimum-absolute-difference
1458-sort-integers-by-the-number-of-1-bits
1533-display-table-of-food-orders-in-a-restaurant
1988-minimize-maximum-pair-sum-in-array
1990-get-biggest-three-rhombus-sums-in-a-grid
2042-maximum-product-difference-between-two-pairs
2112-minimum-difference-between-highest-and-lowest-of-k-scores
2164-two-best-non-overlapping-events
2213-find-all-people-with-secret
2479-meeting-rooms-iii
2505-number-of-good-paths
3214-maximize-area-of-square-hole-in-grid
3263-divide-an-array-into-subarrays-with-minimum-cost-i
3276-minimum-number-of-pushes-to-type-word-ii
3334-apple-redistribution-into-boxes
3351-maximize-happiness-of-selected-children
3721-count-mentions-per-user
3819-count-covered-buildings
3934-coupon-code-validator
4154-maximum-bitwise-and-after-increment-operations

Two Pointers

0018-4sum
0028-find-the-index-of-the-first-occurrence-in-a-string
0321-create-maximum-number
0481-magical-string
1831-ways-to-split-array-into-three-subarrays
1988-minimize-maximum-pair-sum-in-array
3526-minimum-number-of-flips-to-make-binary-grid-palindromic-i
4221-longest-almost-palindromic-substring

Stack

0085-maximal-rectangle
0321-create-maximum-number
0394-decode-string
1298-reverse-substrings-between-each-pair-of-parentheses
1305-number-of-visible-people-in-a-queue
1756-minimum-deletions-to-make-string-balanced

Greedy

0321-create-maximum-number
0330-patching-array
0992-delete-columns-to-make-sorted-ii
1807-partitioning-into-minimum-number-of-deci-binary-numbers
1988-minimize-maximum-pair-sum-in-array
2089-maximum-matrix-sum
2710-minimum-operations-to-reduce-an-integer-to-0
2811-determine-the-minimum-sum-of-a-k-avoiding-array
3276-minimum-number-of-pushes-to-type-word-ii
3334-apple-redistribution-into-boxes
3351-maximize-happiness-of-selected-children
3999-minimum-operations-to-transform-string
4061-minimum-swaps-to-avoid-forbidden-values
4154-maximum-bitwise-and-after-increment-operations

Monotonic Stack

0085-maximal-rectangle
0321-create-maximum-number
1305-number-of-visible-people-in-a-queue

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0214-shortest-palindrome
1508-longest-happy-prefix
3290-number-of-subarrays-that-match-a-pattern-ii

Math

0066-plus-one
0089-gray-code
0233-number-of-digit-one
0382-linked-list-random-node
0767-prime-number-of-set-bits-in-binary-representation
0795-k-th-symbol-in-grammar
0870-magic-squares-in-grid
0914-random-point-in-non-overlapping-rectangles
1284-four-divisors
1395-minimum-time-visiting-all-points
1800-concatenation-of-consecutive-binary-numbers
1990-get-biggest-three-rhombus-sums-in-a-grid
1996-number-of-ways-to-rearrange-sticks-with-k-sticks-visible
2031-egg-drop-with-2-eggs-and-n-floors
2206-detonate-the-maximum-bombs
2233-number-of-smooth-descent-periods-of-a-stock
2251-number-of-ways-to-divide-a-long-corridor
2811-determine-the-minimum-sum-of-a-k-avoiding-array
3325-find-the-largest-area-of-square-inside-two-rectangles
3416-sum-of-digit-differences-of-all-pairs
3721-count-mentions-per-user
3754-maximum-manhattan-distance-after-k-changes
3983-minimum-operations-to-equalize-binary-string
4048-minimum-time-to-complete-all-deliveries
4136-concatenate-non-zero-digits-and-multiply-by-sum-ii

Simulation

1520-number-of-steps-to-reduce-a-number-in-binary-representation-to-one
1800-concatenation-of-consecutive-binary-numbers
2058-concatenation-of-array
2479-meeting-rooms-iii
3721-count-mentions-per-user
3772-minimum-pair-removal-to-sort-array-ii
3773-minimum-pair-removal-to-sort-array-i

Depth-First Search

0200-number-of-islands
0514-freedom-trail
0721-accounts-merge
0863-sum-of-distances-in-tree
0896-smallest-subtree-with-all-the-deepest-nodes
1116-maximum-level-sum-of-a-binary-tree
1396-count-servers-that-communicate
1465-maximum-product-of-splitted-binary-tree
2206-detonate-the-maximum-bombs
2213-find-all-people-with-secret
3854-maximum-profit-from-trading-stocks-with-discounts

Matrix

0085-maximal-rectangle
0200-number-of-islands
0870-magic-squares-in-grid
1311-largest-magic-square
1331-path-with-maximum-gold
1396-count-servers-that-communicate
1413-maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold
1476-count-negative-numbers-in-a-sorted-matrix
1990-get-biggest-three-rhombus-sums-in-a-grid
2089-maximum-matrix-sum
3404-minimum-number-of-operations-to-satisfy-conditions
3526-minimum-number-of-flips-to-make-binary-grid-palindromic-i
3889-minimum-cost-path-with-teleportations
3986-maximum-path-score-in-a-grid

Trie

0336-palindrome-pairs
0421-maximum-xor-of-two-numbers-in-an-array
3238-minimum-cost-to-convert-string-ii
3356-shortest-uncommon-substring-in-an-array

Union Find

0200-number-of-islands
2213-find-all-people-with-secret

Tree

0863-sum-of-distances-in-tree
0896-smallest-subtree-with-all-the-deepest-nodes
1116-maximum-level-sum-of-a-binary-tree
1465-maximum-product-of-splitted-binary-tree
2505-number-of-good-paths
3854-maximum-profit-from-trading-stocks-with-discounts

Sliding Window

0219-contains-duplicate-ii
0395-longest-substring-with-at-least-k-repeating-characters
0424-longest-repeating-character-replacement
0643-maximum-average-subarray-i
1460-number-of-substrings-containing-all-three-characters
2017-minimum-number-of-flips-to-make-the-binary-string-alternating
2112-minimum-difference-between-highest-and-lowest-of-k-scores
3260-divide-an-array-into-subarrays-with-minimum-cost-ii
3267-find-longest-special-substring-that-occurs-thrice-i
3980-best-time-to-buy-and-sell-stock-using-strategy

Prefix Sum

0914-random-point-in-non-overlapping-rectangles
1311-largest-magic-square
1413-maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold
1831-ways-to-split-array-into-three-subarrays
1833-find-the-highest-altitude
1990-get-biggest-three-rhombus-sums-in-a-grid
2576-minimum-penalty-for-a-shop
3406-find-all-possible-stable-binary-arrays-i
3407-find-all-possible-stable-binary-arrays-ii
3980-best-time-to-buy-and-sell-stock-using-strategy
4136-concatenate-non-zero-digits-and-multiply-by-sum-ii

Graph

0863-sum-of-distances-in-tree
2213-find-all-people-with-secret

Binary Search

0914-random-point-in-non-overlapping-rectangles
1232-sum-of-mutated-array-closest-to-target
1413-maximum-side-length-of-a-square-with-sum-less-than-or-equal-to-threshold
1476-count-negative-numbers-in-a-sorted-matrix
1831-ways-to-split-array-into-three-subarrays
2164-two-best-non-overlapping-events
2430-number-of-excellent-pairs
3267-find-longest-special-substring-that-occurs-thrice-i
3763-separate-squares-i
3775-separate-squares-ii
4048-minimum-time-to-complete-all-deliveries

Heap (Priority Queue)

1990-get-biggest-three-rhombus-sums-in-a-grid
2164-two-best-non-overlapping-events
2479-meeting-rooms-iii
3260-divide-an-array-into-subarrays-with-minimum-cost-ii
3772-minimum-pair-removal-to-sort-array-ii
3773-minimum-pair-removal-to-sort-array-i
3887-minimum-cost-path-with-edge-reversals

Combinatorics

1996-number-of-ways-to-rearrange-sticks-with-k-sticks-visible

Recursion

0233-number-of-digit-one
0394-decode-string
0795-k-th-symbol-in-grammar

Rolling Hash

0214-shortest-palindrome
1508-longest-happy-prefix
3290-number-of-subarrays-that-match-a-pattern-ii

Hash Function

0214-shortest-palindrome
1508-longest-happy-prefix
3290-number-of-subarrays-that-match-a-pattern-ii

Counting

1396-count-servers-that-communicate
1458-sort-integers-by-the-number-of-1-bits
2053-check-if-all-characters-have-equal-number-of-occurrences
3267-find-longest-special-substring-that-occurs-thrice-i
3276-minimum-number-of-pushes-to-type-word-ii
3416-sum-of-digit-differences-of-all-pairs
3754-maximum-manhattan-distance-after-k-changes
4061-minimum-swaps-to-avoid-forbidden-values

Binary Tree

0896-smallest-subtree-with-all-the-deepest-nodes
1116-maximum-level-sum-of-a-binary-tree
1465-maximum-product-of-splitted-binary-tree

Linked List

0382-linked-list-random-node
3772-minimum-pair-removal-to-sort-array-ii
3773-minimum-pair-removal-to-sort-array-i

Reservoir Sampling

0382-linked-list-random-node
0914-random-point-in-non-overlapping-rectangles

Randomized

0382-linked-list-random-node
0914-random-point-in-non-overlapping-rectangles

Ordered Set

0914-random-point-in-non-overlapping-rectangles
1533-display-table-of-food-orders-in-a-restaurant
3772-minimum-pair-removal-to-sort-array-ii
3773-minimum-pair-removal-to-sort-array-i
3983-minimum-operations-to-equalize-binary-string

Divide and Conquer

0395-longest-substring-with-at-least-k-repeating-characters
0763-special-binary-string
0954-maximum-sum-circular-subarray
3941-number-of-integers-with-popcount-depth-equal-to-k-ii

Queue

0954-maximum-sum-circular-subarray

Monotonic Queue

0954-maximum-sum-circular-subarray

Geometry

1395-minimum-time-visiting-all-points
2206-detonate-the-maximum-bombs
3325-find-the-largest-area-of-square-inside-two-rectangles

Segment Tree

3775-separate-squares-ii
3941-number-of-integers-with-popcount-depth-equal-to-k-ii

Line Sweep

3775-separate-squares-ii

Enumeration

3250-maximum-square-area-by-removing-fences-from-a-field
3263-divide-an-array-into-subarrays-with-minimum-cost-i

Doubly-Linked List

3772-minimum-pair-removal-to-sort-array-ii
3773-minimum-pair-removal-to-sort-array-i

Graph Theory

2206-detonate-the-maximum-bombs
2505-number-of-good-paths
3235-minimum-cost-to-convert-string-i
3238-minimum-cost-to-convert-string-ii
3887-minimum-cost-path-with-edge-reversals

Shortest Path

3235-minimum-cost-to-convert-string-i
3238-minimum-cost-to-convert-string-ii
3887-minimum-cost-path-with-edge-reversals

Union-Find

0721-accounts-merge
1396-count-servers-that-communicate
2505-number-of-good-paths
3983-minimum-operations-to-equalize-binary-string

Binary Indexed Tree

3941-number-of-integers-with-popcount-depth-equal-to-k-ii