DSA Practice

Python solutions for data structures, algorithms, and LeetCode practice problems. The repository is organized by topic so related patterns are easy to review together.

Repository Structure

.
├── arrays/
│   ├── lc_1_two_sum.py
│   ├── lc_39_combination_sum.py
│   ├── lc_46_permutations.py
│   ├── lc_78_subsets.py
│   ├── lc_877_stone_game.py
│   ├── lc_1140_stone_game_II.py
│   ├── lc_1291_sequential_digits.py
│   ├── lc_1331_rank_transform_of_an_array.py
│   ├── lc_1406_stone_game_III.py
│   ├── lc_1464_maximum_product_of_two_elements_in_an_array.py
│   ├── lc_1477_find_two_non_overlapping_sub_arrays_each_with_target_sum.py
│   ├── lc_1510_stone_game_IV.py
│   ├── lc_1658_minimum_operations_to_reduce_x_to_zero.py
│   ├── lc_1979_greatest_common_divisor_of_array.py
│   ├── lc_2069_walking_robot_simulation_II.py
│   ├── lc_2091_removing_minimum_and_maximum.py
│   ├── lc_2574_left_and_right_sum_differences.py
│   ├── lc_2948_make_lexicographically_smallest_array_by_swapping_elements.py
│   ├── lc_3069_distribute_elements_into_two_arrays_I.py
│   ├── lc_3483_unique-3-digit-even-numbers.py
│   ├── lc_3524_find_x_value_of_array_I.py
│   ├── lc_3689_maximum_total_subarray_value_I.py
│   ├── lc_3731_find_missing_elements.py
│   ├── lc_3903_smallest_stable_index_I.py
│   └── lc_3904_smallest_stable_index_II.py
├── binary-search/
│   └── lc_154_rotated_sorted_arrayII.py
├── binary-trees/
│   ├── lc_2196_create_binary_trees_from_description.py
│   └── lc_2265_count_nodes_equal_to_average_of_subtree.py
├── DSA quest/
│   ├── Array I/
│   │   ├── Q1.py
│   │   ├── Q2.py
│   │   └── Q3.py
│   ├── Array II/
│   │   ├── Q1.py
│   │   ├── Q2.py
│   │   └── Q3.py
│   ├── Monotonic Stack I/
│   │   └── Q1.py
│   └── Stack /
│       ├── Q1.py
│       ├── Q2.py
│       └── Q3.py
├── strings/
│   ├── lc_32_longest_valid_parentheses.py
│   ├── lc_1520_maximum_number_of_non_overlapping_substrings.py
│   ├── lc_3014_minimum_number_of_pushes_to_type_word_I.py
│   ├── lc_3090_maximum_length_substring.py
│   ├── lc_3345_smallest_divisible_digit_product_I.py
│   ├── lc_3498_reverse_degree_of_a_string.py
│   ├── lc_3517_smallest_palindromic_rearrangement_I.py
│   ├── lc_3612_process_string_with_special_operations.py
│   └── lc_3751_total_waviness_of_numbers_in_range_I.py
├── lc_836_rectangle_overlap.py
├── lc_1288_remove_covered_intervals.py
├── lc_1401_circles_and_rectangles_overlapping.py
├── lc_1621_number_of_sets_of_k_overlapping_line_segments.py
├── lc_3336_subsequences_with_equal_gcd.py
├── lc_3622_check_divisibility_by_digit_sum_and_product.py
├── lc_3754_concatenate_non_zero_digits_and_multiply_by_sum_I.py
├── lc_3756_concatenate_non_zero_digits_and_multiply_by_sum_II.py
├── lc_3870_count_commas_in_range_I.py
├── lc_3871_count_commas_in_range_II.py
└── practice.ipynb

Solved Problems

Arrays

File	Problem
arrays/lc_1_two_sum.py	LeetCode 1: Two Sum
arrays/lc_39_combination_sum.py	LeetCode 39: Combination Sum
arrays/lc_46_permutations.py	LeetCode 46: Permutations
arrays/lc_78_subsets.py	LeetCode 78: Subsets
arrays/lc_877_stone_game.py	LeetCode 877: Stone Game
arrays/lc_1140_stone_game_II.py	LeetCode 1140: Stone Game II
arrays/lc_1291_sequential_digits.py	LeetCode 1291: Sequential Digits
arrays/lc_1331_rank_transform_of_an_array.py	LeetCode 1331: Rank Transform of an Array
arrays/lc_1406_stone_game_III.py	LeetCode 1406: Stone Game III
arrays/lc_1464_maximum_product_of_two_elements_in_an_array.py	LeetCode 1464: Maximum Product of Two Elements in an Array
arrays/lc_1477_find_two_non_overlapping_sub_arrays_each_with_target_sum.py	LeetCode 1477: Find Two Non-overlapping Sub-arrays Each With Target Sum
arrays/lc_1510_stone_game_IV.py	LeetCode 1510: Stone Game IV
arrays/lc_1658_minimum_operations_to_reduce_x_to_zero.py	LeetCode 1658: Minimum Operations to Reduce X to Zero
arrays/lc_1979_greatest_common_divisor_of_array.py	LeetCode 1979: Find Greatest Common Divisor of Array
arrays/lc_2069_walking_robot_simulation_II.py	LeetCode 2069: Walking Robot Simulation II
arrays/lc_2091_removing_minimum_and_maximum.py	LeetCode 2091: Removing Minimum and Maximum From Array
arrays/lc_2574_left_and_right_sum_differences.py	LeetCode 2574: Left and Right Sum Differences
arrays/lc_2948_make_lexicographically_smallest_array_by_swapping_elements.py	LeetCode 2948: Make Lexicographically Smallest Array by Swapping Elements
arrays/lc_3069_distribute_elements_into_two_arrays_I.py	LeetCode 3069: Distribute Elements Into Two Arrays I
arrays/lc_3483_unique-3-digit-even-numbers.py	LeetCode 3483: Unique 3-Digit Even Numbers
arrays/lc_3524_find_x_value_of_array_I.py	LeetCode 3524: Find X Value of Array I
arrays/lc_3689_maximum_total_subarray_value_I.py	LeetCode 3689: Maximum Total Subarray Value I
arrays/lc_3731_find_missing_elements.py	LeetCode 3731: Find Missing Elements
arrays/lc_3903_smallest_stable_index_I.py	LeetCode 3903: Smallest Stable Index I
arrays/lc_3904_smallest_stable_index_II.py	LeetCode 3904: Smallest Stable Index II

Binary Search

File	Problem
binary-search/lc_154_rotated_sorted_arrayII.py	LeetCode 154: Find Minimum in Rotated Sorted Array II

Binary Trees

File	Problem
binary-trees/lc_2196_create_binary_trees_from_description.py	LeetCode 2196: Create Binary Tree From Descriptions
binary-trees/lc_2265_count_nodes_equal_to_average_of_subtree.py	LeetCode 2265: Count Nodes Equal to Average of Subtree

Strings

File	Problem
strings/lc_32_longest_valid_parentheses.py	LeetCode 32: Longest Valid Parentheses
strings/lc_1520_maximum_number_of_non_overlapping_substrings.py	LeetCode 1520: Maximum Number of Non-Overlapping Substrings
strings/lc_3014_minimum_number_of_pushes_to_type_word_I.py	LeetCode 3014: Minimum Number of Pushes to Type Word I
strings/lc_3090_maximum_length_substring.py	LeetCode 3090: Maximum Length Substring with Two Occurrences
strings/lc_3345_smallest_divisible_digit_product_I.py	LeetCode 3345: Smallest Divisible Digit Product I
strings/lc_3498_reverse_degree_of_a_string.py	LeetCode 3498: Reverse Degree of a String
strings/lc_3517_smallest_palindromic_rearrangement_I.py	LeetCode 3517: Smallest Palindromic Rearrangement I
strings/lc_3612_process_string_with_special_operations.py	LeetCode 3612: Process String with Special Operations I
strings/lc_3751_total_waviness_of_numbers_in_range_I.py	LeetCode 3751: Total Waviness of Numbers in Range I

Miscellaneous LeetCode

File	Problem
lc_836_rectangle_overlap.py	LeetCode 836: Rectangle Overlap
lc_1288_remove_covered_intervals.py	LeetCode 1288: Remove Covered Intervals
lc_1401_circles_and_rectangles_overlapping.py	LeetCode 1401: Circle and Rectangle Overlapping
lc_1621_number_of_sets_of_k_overlapping_line_segments.py	LeetCode 1621: Number of Sets of K Non-Overlapping Line Segments
lc_3336_subsequences_with_equal_gcd.py	LeetCode 3336: Find the Number of Subsequences With Equal GCD
lc_3622_check_divisibility_by_digit_sum_and_product.py	LeetCode 3622: Check Divisibility by Digit Sum and Product
lc_3754_concatenate_non_zero_digits_and_multiply_by_sum_I.py	LeetCode 3754: Concatenate Non-Zero Digits and Multiply by Sum I
lc_3756_concatenate_non_zero_digits_and_multiply_by_sum_II.py	LeetCode 3756: Concatenate Non-Zero Digits and Multiply by Sum II
lc_3870_count_commas_in_range_I.py	LeetCode 3870: Count Commas in Range I
lc_3871_count_commas_in_range_II.py	LeetCode 3871: Count Commas in Range II

DSA Quest

Folder	Contents
DSA quest/Array I/	Practice questions Q1.py to Q3.py
DSA quest/Array II/	Practice questions Q1.py to Q3.py
DSA quest/Monotonic Stack I/	Practice question Q1.py
DSA quest/Stack /	Practice questions Q1.py to Q3.py

Naming Convention

LeetCode solution files generally use:

lc_<problem_number>_<problem_slug>.py

This keeps files searchable by problem number, title, and topic.