LeetCode Problem Solutions

This repository contains my solutions to various LeetCode problems that I solve during my practice sessions.

📚 About

✍️ Each file corresponds to a single LeetCode problem solution.
📄 Solutions are uploaded as I solve them — no strict folder structure.
🧠 Focused on improving problem-solving skills and algorithmic thinking.

🛠️ Languages Used

Python (mainly)
(Other languages may be added over time)

🚀 How to Use

Clone the repository:

git clone https://github.com/Minhaj401/Leetcode.git

Browse through the files.

Each file is typically named after the problem title.

🌟 Notes

Solutions are self-written unless otherwise mentioned.
Some problems might include multiple approaches inside the same file.
Code is tested against LeetCode test cases.
If a solution isn't optimal, feel free to open a discussion or issue!

📬 Contact

LeetCode Topics

Stack


0071-simplify-path
0094-binary-tree-inorder-traversal
0581-shortest-unsorted-continuous-subarray
0844-backspace-string-compare
1021-remove-outermost-parentheses
1544-make-the-string-great
3174-clear-digits

Tree


0094-binary-tree-inorder-traversal

Depth-First Search


0094-binary-tree-inorder-traversal

Binary Tree


0094-binary-tree-inorder-traversal

Array


0015-3sum
0016-3sum-closest
0026-remove-duplicates-from-sorted-array
0075-sort-colors
0217-contains-duplicate
0581-shortest-unsorted-continuous-subarray
0628-maximum-product-of-three-numbers
0704-binary-search
0881-boats-to-save-people
0948-bag-of-tokens
0961-n-repeated-element-in-size-2n-array
1051-height-checker
1331-rank-transform-of-an-array
1637-widest-vertical-area-between-two-points-containing-no-points
2079-watering-plants
2105-watering-plants-ii
2545-sort-the-students-by-their-kth-score
2610-convert-an-array-into-a-2d-array-with-conditions
3974-maximum-total-sum-of-k-selected-elements

Sorting


0015-3sum
0016-3sum-closest
0075-sort-colors
0217-contains-duplicate
0581-shortest-unsorted-continuous-subarray
0628-maximum-product-of-three-numbers
0881-boats-to-save-people
0948-bag-of-tokens
1051-height-checker
1331-rank-transform-of-an-array
1637-widest-vertical-area-between-two-points-containing-no-points
2545-sort-the-students-by-their-kth-score
3974-maximum-total-sum-of-k-selected-elements

String


0071-simplify-path
0345-reverse-vowels-of-a-string
0387-first-unique-character-in-a-string
0415-add-strings
0844-backspace-string-compare
1021-remove-outermost-parentheses
1544-make-the-string-great
2351-first-letter-to-appear-twice
3110-score-of-a-string
3174-clear-digits

Two Pointers


0015-3sum
0016-3sum-closest
0026-remove-duplicates-from-sorted-array
0075-sort-colors
0202-happy-number
0345-reverse-vowels-of-a-string
0581-shortest-unsorted-continuous-subarray
0844-backspace-string-compare
0881-boats-to-save-people
0948-bag-of-tokens
2105-watering-plants-ii

Greedy


0581-shortest-unsorted-continuous-subarray
0881-boats-to-save-people
0948-bag-of-tokens
3974-maximum-total-sum-of-k-selected-elements

Hash Table


0202-happy-number
0217-contains-duplicate
0387-first-unique-character-in-a-string
0961-n-repeated-element-in-size-2n-array
1331-rank-transform-of-an-array
2351-first-letter-to-appear-twice
2610-convert-an-array-into-a-2d-array-with-conditions

Monotonic Stack


0581-shortest-unsorted-continuous-subarray

Math


0070-climbing-stairs
0202-happy-number
0231-power-of-two
0415-add-strings
0507-perfect-number
0628-maximum-product-of-three-numbers
0728-self-dividing-numbers
1025-divisor-game

Matrix


2545-sort-the-students-by-their-kth-score

Simulation


0415-add-strings
0844-backspace-string-compare
2079-watering-plants
2105-watering-plants-ii
3174-clear-digits

Database


0175-combine-two-tables
0181-employees-earning-more-than-their-managers

Pigeonhole Principle


0961-n-repeated-element-in-size-2n-array

Floyd's Cycle Finding Algorithm


0202-happy-number

Dynamic Programming


0070-climbing-stairs
1025-divisor-game

Brainteaser


1025-divisor-game

Game Theory


1025-divisor-game

Impartial Game


1025-divisor-game

Bit Manipulation


0191-number-of-1-bits
0231-power-of-two
2351-first-letter-to-appear-twice

Recursion


0231-power-of-two

Divide and Conquer


0191-number-of-1-bits

Memoization


0070-climbing-stairs

Queue


0387-first-unique-character-in-a-string
0933-number-of-recent-calls

Counting


0387-first-unique-character-in-a-string
2351-first-letter-to-appear-twice

Linked List


0083-remove-duplicates-from-sorted-list

Binary Search


0704-binary-search

Bracket Sequences


1021-remove-outermost-parentheses

Counting Sort


1051-height-checker

Bubble Sort


1051-height-checker

Design


0933-number-of-recent-calls

Data Stream


0933-number-of-recent-calls

Timsort


0881-boats-to-save-people

Name		Name	Last commit message	Last commit date
0015-3sum		0015-3sum
0016-3sum-closest		0016-3sum-closest
0026-remove-duplicates-from-sorted-array		0026-remove-duplicates-from-sorted-array
0070-climbing-stairs		0070-climbing-stairs
0071-simplify-path		0071-simplify-path
0075-sort-colors		0075-sort-colors
0083-remove-duplicates-from-sorted-list		0083-remove-duplicates-from-sorted-list
0094-binary-tree-inorder-traversal		0094-binary-tree-inorder-traversal
0175-combine-two-tables		0175-combine-two-tables
0176-second-highest-salary		0176-second-highest-salary
0181-employees-earning-more-than-their-managers		0181-employees-earning-more-than-their-managers
0191-number-of-1-bits		0191-number-of-1-bits
0202-happy-number		0202-happy-number
0217-contains-duplicate		0217-contains-duplicate
0231-power-of-two		0231-power-of-two
0345-reverse-vowels-of-a-string		0345-reverse-vowels-of-a-string
0387-first-unique-character-in-a-string		0387-first-unique-character-in-a-string
0415-add-strings		0415-add-strings
0507-perfect-number		0507-perfect-number
0581-shortest-unsorted-continuous-subarray		0581-shortest-unsorted-continuous-subarray
0628-maximum-product-of-three-numbers		0628-maximum-product-of-three-numbers
0704-binary-search		0704-binary-search
0728-self-dividing-numbers		0728-self-dividing-numbers
0844-backspace-string-compare		0844-backspace-string-compare
0881-boats-to-save-people		0881-boats-to-save-people
0933-number-of-recent-calls		0933-number-of-recent-calls
0948-bag-of-tokens		0948-bag-of-tokens
0961-n-repeated-element-in-size-2n-array		0961-n-repeated-element-in-size-2n-array
1021-remove-outermost-parentheses		1021-remove-outermost-parentheses
1025-divisor-game		1025-divisor-game
1051-height-checker		1051-height-checker
1331-rank-transform-of-an-array		1331-rank-transform-of-an-array
1544-make-the-string-great		1544-make-the-string-great
1637-widest-vertical-area-between-two-points-containing-no-points		1637-widest-vertical-area-between-two-points-containing-no-points
2079-watering-plants		2079-watering-plants
2105-watering-plants-ii		2105-watering-plants-ii
2351-first-letter-to-appear-twice		2351-first-letter-to-appear-twice
2545-sort-the-students-by-their-kth-score		2545-sort-the-students-by-their-kth-score
2610-convert-an-array-into-a-2d-array-with-conditions		2610-convert-an-array-into-a-2d-array-with-conditions
3110-score-of-a-string		3110-score-of-a-string
3174-clear-digits		3174-clear-digits
3974-maximum-total-sum-of-k-selected-elements		3974-maximum-total-sum-of-k-selected-elements
Add_Two_Integers.py		Add_Two_Integers.py
Palindrome_Number.py		Palindrome_Number.py
README.md		README.md
Smallest_Even_Multiple.py		Smallest_Even_Multiple.py
alternating-digit-sum.py		alternating-digit-sum.py
ant-on-the-boundary.py		ant-on-the-boundary.py
average-salary-excluding-the-minimum-and-maximum-salary.py		average-salary-excluding-the-minimum-and-maximum-salary.py
average-value-of-even-numbers-that-are-divisible-by-three.py		average-value-of-even-numbers-that-are-divisible-by-three.py
calculate-delayed-arrival-time.py		calculate-delayed-arrival-time.py
can-make-arithmetic-progression-from-sequence.py		can-make-arithmetic-progression-from-sequence.py
capitalize-the-title.py		capitalize-the-title.py
change-data-type.py		change-data-type.py
check-if-the-sentence-is-pangram.py		check-if-the-sentence-is-pangram.py
complex-number-multiplication.py		complex-number-multiplication.py
concatenation-of-array.py		concatenation-of-array.py
convert-date-to-binary.py		convert-date-to-binary.py
convert-the-temperature.py		convert-the-temperature.py
count-items-matching-a-rule.py		count-items-matching-a-rule.py
count-negative-numbers-in-a-sorted-matrix.py		count-negative-numbers-in-a-sorted-matrix.py
count-number-of-distinct-integers-after-reverse-operations.py		count-number-of-distinct-integers-after-reverse-operations.py
count-odd-numbers-in-an-interval-range.py		count-odd-numbers-in-an-interval-range.py
count-of-matches-in-tournament.py		count-of-matches-in-tournament.py
count-the-digits-that-divide-a-number.py		count-the-digits-that-divide-a-number.py
create-a-dataframe-from-list.py		create-a-dataframe-from-list.py
create-a-new-column.py		create-a-new-column.py
defanging-an-ip-address.py		defanging-an-ip-address.py
difference-between-element-sum-and-digit-sum-of-an-array.py		difference-between-element-sum-and-digit-sum-of-an-array.py
display-the-first-three-rows.py		display-the-first-three-rows.py
divisible-and-non-divisible-sums-difference.py		divisible-and-non-divisible-sums-difference.py
drop-missing-data.py		drop-missing-data.py
fibonacci-number.py		fibonacci-number.py
final-value-of-variable-after-performing-operations.py		final-value-of-variable-after-performing-operations.py
find-first-palindromic-string-in-the-array.py		find-first-palindromic-string-in-the-array.py
find-greatest-common-divisor-of-array.py		find-greatest-common-divisor-of-array.py
find-if-digit-game-can-be-won.py		find-if-digit-game-can-be-won.py
find-lucky-integer-in-an-array.py		find-lucky-integer-in-an-array.py
find-minimum-operations-to-make-all-elements-divisible-by-three.py		find-minimum-operations-to-make-all-elements-divisible-by-three.py
find-the-difference-of-two-arrays.py		find-the-difference-of-two-arrays.py
find-the-difference.py		find-the-difference.py
find-the-index-of-the-first-occurrence-in-a-string.py		find-the-index-of-the-first-occurrence-in-a-string.py
find-the-integer-added-to-array-i.py		find-the-integer-added-to-array-i.py
find-the-maximum-achievable-number.py		find-the-maximum-achievable-number.py
find-the-original-array-of-prefix-xor.py		find-the-original-array-of-prefix-xor.py
find-triangular-sum-of-an-array.py		find-triangular-sum-of-an-array.py
find-words-containing-character.py		find-words-containing-character.py
fizz-buzz.py		fizz-buzz.py
get-the-size-of-a-dataframe.py		get-the-size-of-a-dataframe.py
goal-parser-interpretation.py		goal-parser-interpretation.py
harshad-number.py		harshad-number.py
how-many-numbers-are-smaller-than-the-current-number.py		how-many-numbers-are-smaller-than-the-current-number.py
integer-to-roman.py		integer-to-roman.py
intersection-of-two-arrays.py		intersection-of-two-arrays.py
keep-multiplying-found-values-by-two.py		keep-multiplying-found-values-by-two.py
length-of-last-word.py		length-of-last-word.py
majority-element.py		majority-element.py
maximum-69-number.py		maximum-69-number.py
maximum-number-of-words-found-in-sentences.py		maximum-number-of-words-found-in-sentences.py
minimum-number-of-operations-to-move-all-balls-to-each-box.py		minimum-number-of-operations-to-move-all-balls-to-each-box.py

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