LeetCode Solutions by Darshan

Welcome to my LeetCode solutions repository! This repo contains my solutions to various algorithm and data structure problems from LeetCode, implemented mainly in C++.
The goal of this repo is to track my problem-solving progress, improve my coding skills, and share helpful solutions with the community.

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About

This repository is a personal collection of solutions to LeetCode problems. Each solution aims to provide clear, optimized, and well-commented code for better understanding.
I update this repo regularly as I solve new problems and revise older ones.

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LeetCode Topics

Linked List

0002-add-two-numbers
1267-remove-zero-sum-consecutive-nodes-from-linked-list
2903-insert-greatest-common-divisors-in-linked-list
3501-delete-nodes-from-linked-list-present-in-array

Math

0002-add-two-numbers
0007-reverse-integer
0009-palindrome-number
0043-multiply-strings
0066-plus-one
0189-rotate-array
0231-power-of-two
0268-missing-number
0509-fibonacci-number
0670-maximum-swap
0840-magic-squares-in-grid
0900-reordered-power-of-2
1018-largest-perimeter-triangle
1390-four-divisors
1426-find-n-unique-integers-sum-up-to-zero
1523-count-odd-numbers-in-an-interval-range
1635-number-of-good-pairs
1642-water-bottles
1889-check-if-number-is-a-sum-of-powers-of-three
1925-count-square-sum-triples
1979-find-greatest-common-divisor-of-array
2110-number-of-smooth-descent-periods-of-a-stock
2147-number-of-ways-to-divide-a-long-corridor
2288-count-operations-to-obtain-zero
2610-closest-prime-numbers-in-range
2649-count-total-number-of-colored-cells
2903-insert-greatest-common-divisors-in-linked-list
3172-divisible-and-non-divisible-sums-difference
3190-find-minimum-operations-to-make-all-elements-divisible-by-three
3201-distribute-candies-among-children-ii
3227-find-missing-and-repeated-values
3321-type-of-triangle
3336-water-bottles-ii
3432-count-partitions-with-even-sum-difference
3433-count-mentions-per-user
3512-minimum-operations-to-make-array-sum-divisible-by-k
3515-find-if-digit-game-can-be-won
3577-count-the-number-of-computer-unlocking-permutations
3581-the-two-sneaky-numbers-of-digitville
3623-count-number-of-trapezoids-i
3625-count-number-of-trapezoids-ii
3676-smallest-number-with-all-set-bits
3768-check-if-digits-are-equal-in-string-after-operations-i

Recursion

0002-add-two-numbers
0231-power-of-two
0509-fibonacci-number
1197-parsing-a-boolean-expression
1667-find-kth-bit-in-nth-binary-string

Array

0001-two-sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0036-valid-sudoku
0037-sudoku-solver
0041-first-missing-positive
0066-plus-one
0075-sort-colors
0085-maximal-rectangle
0088-merge-sorted-array
0120-triangle
0121-best-time-to-buy-and-sell-stock
0135-candy
0136-single-number
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0189-rotate-array
0217-contains-duplicate
0219-contains-duplicate-ii
0268-missing-number
0283-move-zeroes
0287-find-the-duplicate-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0448-find-all-numbers-disappeared-in-an-array
0455-assign-cookies
0474-ones-and-zeroes
0611-valid-triangle-number
0645-set-mismatch
0717-1-bit-and-2-bit-characters
0745-find-smallest-letter-greater-than-target
0759-set-intersection-size-at-least-two
0833-bus-routes
0840-magic-squares-in-grid
0934-bitwise-ors-of-subarrays
0941-sort-array-by-parity
0944-delete-columns-to-make-sorted
0955-delete-columns-to-make-sorted-ii
0960-delete-columns-to-make-sorted-iii
0961-n-repeated-element-in-size-2n-array
1002-maximum-width-ramp
1018-largest-perimeter-triangle
1019-squares-of-a-sorted-array
1168-duplicate-zeros
1249-snapshot-array
1262-greatest-sum-divisible-by-three
1293-three-consecutive-odds
1335-maximum-candies-allocated-to-k-children
1351-count-negative-numbers-in-a-sorted-matrix
1390-four-divisors
1402-count-square-submatrices-with-all-ones
1407-group-the-people-given-the-group-size-they-belong-to
1424-maximum-candies-you-can-get-from-boxes
1426-find-n-unique-integers-sum-up-to-zero
1458-max-dot-product-of-two-subsequences
1470-shuffle-the-array
1548-check-if-all-1s-are-at-least-length-k-places-away
1586-longest-subarray-of-1s-after-deleting-one-element
1590-make-sum-divisible-by-p
1635-number-of-good-pairs
1752-check-if-array-is-sorted-and-rotated
1760-check-array-formation-through-concatenation
1834-minimum-number-of-people-to-teach
1929-concatenation-of-array
1970-last-day-where-you-can-still-cross
1975-maximum-matrix-sum
1979-find-greatest-common-divisor-of-array
2023-design-movie-rental-system
2054-two-best-non-overlapping-events
2110-number-of-smooth-descent-periods-of-a-stock
2137-final-value-of-variable-after-performing-operations
2141-maximum-running-time-of-n-computers
2170-count-number-of-maximum-bitwise-or-subsets
2265-partition-array-according-to-given-pivot
2271-rearrange-array-elements-by-sign
2308-divide-array-into-equal-pairs
2316-count-hills-and-valleys-in-an-array
2343-count-unguarded-cells-in-the-grid
2402-meeting-rooms-iii
2435-paths-in-matrix-whose-sum-is-divisible-by-k
2478-longest-nice-subarray
2483-task-scheduler-ii
2498-smallest-subarrays-with-maximum-bitwise-or
2503-longest-subarray-with-maximum-bitwise-and
2529-range-product-queries-of-powers
2614-maximum-count-of-positive-integer-and-negative-integer
2625-increment-submatrices-by-one
2689-rearranging-fruits
2707-merge-two-2d-arrays-by-summing-values
2724-convert-an-array-into-a-2d-array-with-conditions
2755-extra-characters-in-a-string
2766-find-the-prefix-common-array-of-two-arrays
2888-minimum-index-of-a-valid-split
3075-maximize-happiness-of-selected-children
3190-find-minimum-operations-to-make-all-elements-divisible-by-three
3194-find-words-containing-character
3227-find-missing-and-repeated-values
3321-type-of-triangle
3430-count-days-without-meetings
3432-count-partitions-with-even-sum-difference
3433-count-mentions-per-user
3459-find-the-minimum-area-to-cover-all-ones-ii
3461-find-the-minimum-area-to-cover-all-ones-i
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3501-delete-nodes-from-linked-list-present-in-array
3512-minimum-operations-to-make-array-sum-divisible-by-k
3515-find-if-digit-game-can-be-won
3577-count-the-number-of-computer-unlocking-permutations
3581-the-two-sneaky-numbers-of-digitville
3583-count-special-triplets
3606-coupon-code-validator
3610-find-x-sum-of-all-k-long-subarrays-i
3623-count-number-of-trapezoids-i
3625-count-number-of-trapezoids-ii
3648-find-the-maximum-number-of-fruits-collected
3652-best-time-to-buy-and-sell-stock-using-strategy
3789-maximize-subarrays-after-removing-one-conflicting-pair
3819-count-covered-buildings
3827-implement-router
3863-power-grid-maintenance

Hash Table

0001-two-sum
0036-valid-sudoku
0037-sudoku-solver
0041-first-missing-positive
0169-majority-element
0217-contains-duplicate
0219-contains-duplicate-ii
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0448-find-all-numbers-disappeared-in-an-array
0645-set-mismatch
0756-pyramid-transition-matrix
0833-bus-routes
0840-magic-squares-in-grid
0865-smallest-subtree-with-all-the-deepest-nodes
0900-reordered-power-of-2
0920-uncommon-words-from-two-sentences
0961-n-repeated-element-in-size-2n-array
1218-lowest-common-ancestor-of-deepest-leaves
1249-snapshot-array
1267-remove-zero-sum-consecutive-nodes-from-linked-list
1407-group-the-people-given-the-group-size-they-belong-to
1460-number-of-substrings-containing-all-three-characters
1590-make-sum-divisible-by-p
1635-number-of-good-pairs
1760-check-array-formation-through-concatenation
1777-determine-if-two-strings-are-close
1834-minimum-number-of-people-to-teach
2023-design-movie-rental-system
2308-divide-array-into-equal-pairs
2402-meeting-rooms-iii
2483-task-scheduler-ii
2689-rearranging-fruits
2707-merge-two-2d-arrays-by-summing-values
2724-convert-an-array-into-a-2d-array-with-conditions
2755-extra-characters-in-a-string
2766-find-the-prefix-common-array-of-two-arrays
2888-minimum-index-of-a-valid-split
3227-find-missing-and-repeated-values
3501-delete-nodes-from-linked-list-present-in-array
3581-the-two-sneaky-numbers-of-digitville
3583-count-special-triplets
3606-coupon-code-validator
3610-find-x-sum-of-all-k-long-subarrays-i
3623-count-number-of-trapezoids-i
3625-count-number-of-trapezoids-ii
3819-count-covered-buildings
3827-implement-router
3863-power-grid-maintenance

Two Pointers

0026-remove-duplicates-from-sorted-array
0027-remove-element
0075-sort-colors
0088-merge-sorted-array
0125-valid-palindrome
0167-two-sum-ii-input-array-is-sorted
0189-rotate-array
0283-move-zeroes
0287-find-the-duplicate-number
0349-intersection-of-two-arrays
0455-assign-cookies
0611-valid-triangle-number
0680-valid-palindrome-ii
0941-sort-array-by-parity
1002-maximum-width-ramp
1019-squares-of-a-sorted-array
1168-duplicate-zeros
2128-reverse-prefix-of-word
2265-partition-array-according-to-given-pivot
2271-rearrange-array-elements-by-sign
2707-merge-two-2d-arrays-by-summing-values
3683-find-the-lexicographically-largest-string-from-the-box-i

Number Theory

1979-find-greatest-common-divisor-of-array
2610-closest-prime-numbers-in-range
2903-insert-greatest-common-divisors-in-linked-list
3768-check-if-digits-are-equal-in-string-after-operations-i

String

0008-string-to-integer-atoi
0043-multiply-strings
0125-valid-palindrome
0242-valid-anagram
0474-ones-and-zeroes
0680-valid-palindrome-ii
0712-minimum-ascii-delete-sum-for-two-strings
0756-pyramid-transition-matrix
0812-rotate-string
0920-uncommon-words-from-two-sentences
0944-delete-columns-to-make-sorted
0955-delete-columns-to-make-sorted-ii
0960-delete-columns-to-make-sorted-iii
1058-lexicographically-smallest-equivalent-string
1197-parsing-a-boolean-expression
1205-defanging-an-ip-address
1304-longest-happy-string
1460-number-of-substrings-containing-all-three-characters
1667-find-kth-bit-in-nth-binary-string
1777-determine-if-two-strings-are-close
2128-reverse-prefix-of-word
2137-final-value-of-variable-after-performing-operations
2147-number-of-ways-to-divide-a-long-corridor
2211-count-collisions-on-a-road
2483-minimum-penalty-for-a-shop
2755-extra-characters-in-a-string
3194-find-words-containing-character
3312-number-of-changing-keys
3379-score-of-a-string
3606-coupon-code-validator
3683-find-the-lexicographically-largest-string-from-the-box-i
3768-check-if-digits-are-equal-in-string-after-operations-i

Simulation

0043-multiply-strings
1642-water-bottles
1667-find-kth-bit-in-nth-binary-string
1929-concatenation-of-array
2137-final-value-of-variable-after-performing-operations
2211-count-collisions-on-a-road
2265-partition-array-according-to-given-pivot
2271-rearrange-array-elements-by-sign
2288-count-operations-to-obtain-zero
2343-count-unguarded-cells-in-the-grid
2402-meeting-rooms-iii
2408-number-of-people-aware-of-a-secret
2483-task-scheduler-ii
3336-water-bottles-ii
3433-count-mentions-per-user
3768-check-if-digits-are-equal-in-string-after-operations-i

Combinatorics

3201-distribute-candies-among-children-ii
3577-count-the-number-of-computer-unlocking-permutations
3768-check-if-digits-are-equal-in-string-after-operations-i

Backtracking

0037-sudoku-solver
0756-pyramid-transition-matrix
2170-count-number-of-maximum-bitwise-or-subsets

Bit Manipulation

0136-single-number
0231-power-of-two
0268-missing-number
0287-find-the-duplicate-number
0645-set-mismatch
0756-pyramid-transition-matrix
0934-bitwise-ors-of-subarrays
2170-count-number-of-maximum-bitwise-or-subsets
2308-divide-array-into-equal-pairs
2478-longest-nice-subarray
2498-smallest-subarrays-with-maximum-bitwise-or
2503-longest-subarray-with-maximum-bitwise-and
2529-range-product-queries-of-powers
2766-find-the-prefix-common-array-of-two-arrays
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3676-smallest-number-with-all-set-bits

Enumeration

0900-reordered-power-of-2
1925-count-square-sum-triples
2170-count-number-of-maximum-bitwise-or-subsets
3201-distribute-candies-among-children-ii
3459-find-the-minimum-area-to-cover-all-ones-ii
3683-find-the-lexicographically-largest-string-from-the-box-i
3789-maximize-subarrays-after-removing-one-conflicting-pair

Greedy

0135-candy
0455-assign-cookies
0611-valid-triangle-number
0670-maximum-swap
0680-valid-palindrome-ii
0759-set-intersection-size-at-least-two
0955-delete-columns-to-make-sorted-ii
1018-largest-perimeter-triangle
1262-greatest-sum-divisible-by-three
1304-longest-happy-string
1407-group-the-people-given-the-group-size-they-belong-to
1834-minimum-number-of-people-to-teach
1975-maximum-matrix-sum
2141-maximum-running-time-of-n-computers
2689-rearranging-fruits
3075-maximize-happiness-of-selected-children

Counting

0169-majority-element
0347-top-k-frequent-elements
0900-reordered-power-of-2
0920-uncommon-words-from-two-sentences
1635-number-of-good-pairs
1777-determine-if-two-strings-are-close
2308-divide-array-into-equal-pairs
2614-maximum-count-of-positive-integer-and-negative-integer
3583-count-special-triplets

Matrix

0036-valid-sudoku
0037-sudoku-solver
0085-maximal-rectangle
0840-magic-squares-in-grid
1351-count-negative-numbers-in-a-sorted-matrix
1402-count-square-submatrices-with-all-ones
1970-last-day-where-you-can-still-cross
1975-maximum-matrix-sum
2343-count-unguarded-cells-in-the-grid
2435-paths-in-matrix-whose-sum-is-divisible-by-k
2625-increment-submatrices-by-one
3227-find-missing-and-repeated-values
3459-find-the-minimum-area-to-cover-all-ones-ii
3461-find-the-minimum-area-to-cover-all-ones-i
3648-find-the-maximum-number-of-fruits-collected

Binary Search

0167-two-sum-ii-input-array-is-sorted
0268-missing-number
0278-first-bad-version
0287-find-the-duplicate-number
0349-intersection-of-two-arrays
0611-valid-triangle-number
0745-find-smallest-letter-greater-than-target
1249-snapshot-array
1335-maximum-candies-allocated-to-k-children
1351-count-negative-numbers-in-a-sorted-matrix
1970-last-day-where-you-can-still-cross
2054-two-best-non-overlapping-events
2141-maximum-running-time-of-n-computers
2498-smallest-subarrays-with-maximum-bitwise-or
2614-maximum-count-of-positive-integer-and-negative-integer
3827-implement-router

Sorting

0075-sort-colors
0088-merge-sorted-array
0169-majority-element
0217-contains-duplicate
0242-valid-anagram
0268-missing-number
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0455-assign-cookies
0611-valid-triangle-number
0645-set-mismatch
0759-set-intersection-size-at-least-two
0900-reordered-power-of-2
0941-sort-array-by-parity
1018-largest-perimeter-triangle
1019-squares-of-a-sorted-array
1262-greatest-sum-divisible-by-three
1777-determine-if-two-strings-are-close
2054-two-best-non-overlapping-events
2092-find-all-people-with-secret
2141-maximum-running-time-of-n-computers
2402-meeting-rooms-iii
2689-rearranging-fruits
2888-minimum-index-of-a-valid-split
3075-maximize-happiness-of-selected-children
3321-type-of-triangle
3430-count-days-without-meetings
3433-count-mentions-per-user
3606-coupon-code-validator
3819-count-covered-buildings

Stack

0085-maximal-rectangle
1002-maximum-width-ramp
1197-parsing-a-boolean-expression
2128-reverse-prefix-of-word
2211-count-collisions-on-a-road

Monotonic Stack

0085-maximal-rectangle
1002-maximum-width-ramp

Sliding Window

0219-contains-duplicate-ii
1460-number-of-substrings-containing-all-three-characters
1586-longest-subarray-of-1s-after-deleting-one-element
2478-longest-nice-subarray
2498-smallest-subarrays-with-maximum-bitwise-or
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3610-find-x-sum-of-all-k-long-subarrays-i
3652-best-time-to-buy-and-sell-stock-using-strategy

Heap (Priority Queue)

0347-top-k-frequent-elements
1304-longest-happy-string
2023-design-movie-rental-system
2054-two-best-non-overlapping-events
2402-meeting-rooms-iii
3610-find-x-sum-of-all-k-long-subarrays-i
3863-power-grid-maintenance

Queue

2408-number-of-people-aware-of-a-secret
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3827-implement-router

Prefix Sum

1590-make-sum-divisible-by-p
2483-minimum-penalty-for-a-shop
2529-range-product-queries-of-powers
2625-increment-submatrices-by-one
3432-count-partitions-with-even-sum-difference
3475-minimum-operations-to-make-binary-array-elements-equal-to-one-i
3652-best-time-to-buy-and-sell-stock-using-strategy
3789-maximize-subarrays-after-removing-one-conflicting-pair

Interactive

0278-first-bad-version

String Matching

0812-rotate-string

Tree

0865-smallest-subtree-with-all-the-deepest-nodes
1161-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1339-maximum-product-of-splitted-binary-tree
2872-maximum-number-of-k-divisible-components

Depth-First Search

0865-smallest-subtree-with-all-the-deepest-nodes
1161-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1339-maximum-product-of-splitted-binary-tree
1970-last-day-where-you-can-still-cross
2092-find-all-people-with-secret
2872-maximum-number-of-k-divisible-components
3863-power-grid-maintenance

Breadth-First Search

0833-bus-routes
0865-smallest-subtree-with-all-the-deepest-nodes
1161-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1424-maximum-candies-you-can-get-from-boxes
1970-last-day-where-you-can-still-cross
2092-find-all-people-with-secret
3863-power-grid-maintenance

Binary Tree

0865-smallest-subtree-with-all-the-deepest-nodes
1161-maximum-level-sum-of-a-binary-tree
1218-lowest-common-ancestor-of-deepest-leaves
1339-maximum-product-of-splitted-binary-tree

Design

1249-snapshot-array
2023-design-movie-rental-system
3827-implement-router

Dynamic Programming

0085-maximal-rectangle
0120-triangle
0121-best-time-to-buy-and-sell-stock
0474-ones-and-zeroes
0509-fibonacci-number
0712-minimum-ascii-delete-sum-for-two-strings
0934-bitwise-ors-of-subarrays
0960-delete-columns-to-make-sorted-iii
1262-greatest-sum-divisible-by-three
1402-count-square-submatrices-with-all-ones
1411-number-of-ways-to-paint-n-3-grid
1458-max-dot-product-of-two-subsequences
1586-longest-subarray-of-1s-after-deleting-one-element
2028-the-earliest-and-latest-rounds-where-players-compete
2054-two-best-non-overlapping-events
2110-number-of-smooth-descent-periods-of-a-stock
2147-number-of-ways-to-divide-a-long-corridor
2408-number-of-people-aware-of-a-secret
2435-paths-in-matrix-whose-sum-is-divisible-by-k
2755-extra-characters-in-a-string
2882-ways-to-express-an-integer-as-sum-of-powers
3648-find-the-maximum-number-of-fruits-collected

Trie

2755-extra-characters-in-a-string

Graph

1424-maximum-candies-you-can-get-from-boxes
2092-find-all-people-with-secret
3863-power-grid-maintenance

Union Find

1058-lexicographically-smallest-equivalent-string
1970-last-day-where-you-can-still-cross
2092-find-all-people-with-secret
3863-power-grid-maintenance

Memoization

0509-fibonacci-number
2028-the-earliest-and-latest-rounds-where-players-compete

Segment Tree

3789-maximize-subarrays-after-removing-one-conflicting-pair

Brainteaser

2503-longest-subarray-with-maximum-bitwise-and
3577-count-the-number-of-computer-unlocking-permutations

Divide and Conquer

0169-majority-element
0347-top-k-frequent-elements

Bucket Sort

0347-top-k-frequent-elements

Quickselect

0347-top-k-frequent-elements

Ordered Set

2023-design-movie-rental-system
3827-implement-router
3863-power-grid-maintenance

Geometry

3623-count-number-of-trapezoids-i
3625-count-number-of-trapezoids-ii