> ## Documentation Index > Fetch the complete documentation index at: https://leetcode-py.wisl.dev/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > leetcode-py is a Python LeetCode practice environment generator with one CLI: lcpy. It is not a service or platform. > Each problem is a directory under leetcode/ with README.md, solution.py, test_solution.py, helpers.py, and playground.ipynb. lcpy gen creates them from JSON templates bundled with the package. > Examples are backed by tests; copy them verbatim. # Grind 75 > All 75 Grind 75 problems with links to each problem and solution. Grind 75 holds 75 problems (23 Easy, 43 Medium, 9 Hard). Generate the whole collection into the current directory: ```bash theme={"theme":{"light":"github-light","dark":"github-dark"}} lcpy gen -t grind-75 ``` | # | Problem | Difficulty | Solution | | ---- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------- | ----------------------------------------------------------------------------------------------------------------------------------------------- | | 1 | [Two Sum](https://github.com/wislertt/leetcode-py/blob/main/leetcode/two_sum/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/two_sum/solution.py) | | 3 | [Longest Substring Without Repeating Characters](https://github.com/wislertt/leetcode-py/blob/main/leetcode/longest_substring_without_repeating_characters/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/longest_substring_without_repeating_characters/solution.py) | | 5 | [Longest Palindromic Substring](https://github.com/wislertt/leetcode-py/blob/main/leetcode/longest_palindromic_substring/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/longest_palindromic_substring/solution.py) | | 8 | [String to Integer (atoi)](https://github.com/wislertt/leetcode-py/blob/main/leetcode/string_to_integer_atoi/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/string_to_integer_atoi/solution.py) | | 11 | [Container With Most Water](https://github.com/wislertt/leetcode-py/blob/main/leetcode/container_with_most_water/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/container_with_most_water/solution.py) | | 15 | [3Sum](https://github.com/wislertt/leetcode-py/blob/main/leetcode/three_sum/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/three_sum/solution.py) | | 17 | [Letter Combinations of a Phone Number](https://github.com/wislertt/leetcode-py/blob/main/leetcode/letter_combinations_of_a_phone_number/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/letter_combinations_of_a_phone_number/solution.py) | | 20 | [Valid Parentheses](https://github.com/wislertt/leetcode-py/blob/main/leetcode/valid_parentheses/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/valid_parentheses/solution.py) | | 21 | [Merge Two Sorted Lists](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_two_sorted_lists/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_two_sorted_lists/solution.py) | | 23 | [Merge k Sorted Lists](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_k_sorted_lists/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_k_sorted_lists/solution.py) | | 33 | [Search in Rotated Sorted Array](https://github.com/wislertt/leetcode-py/blob/main/leetcode/search_in_rotated_sorted_array/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/search_in_rotated_sorted_array/solution.py) | | 39 | [Combination Sum](https://github.com/wislertt/leetcode-py/blob/main/leetcode/combination_sum/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/combination_sum/solution.py) | | 42 | [Trapping Rain Water](https://github.com/wislertt/leetcode-py/blob/main/leetcode/trapping_rain_water/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/trapping_rain_water/solution.py) | | 46 | [Permutations](https://github.com/wislertt/leetcode-py/blob/main/leetcode/permutations/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/permutations/solution.py) | | 53 | [Maximum Subarray](https://github.com/wislertt/leetcode-py/blob/main/leetcode/maximum_subarray/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/maximum_subarray/solution.py) | | 54 | [Spiral Matrix](https://github.com/wislertt/leetcode-py/blob/main/leetcode/spiral_matrix/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/spiral_matrix/solution.py) | | 56 | [Merge Intervals](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_intervals/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_intervals/solution.py) | | 57 | [Insert Interval](https://github.com/wislertt/leetcode-py/blob/main/leetcode/insert_interval/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/insert_interval/solution.py) | | 62 | [Unique Paths](https://github.com/wislertt/leetcode-py/blob/main/leetcode/unique_paths/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/unique_paths/solution.py) | | 67 | [Add Binary](https://github.com/wislertt/leetcode-py/blob/main/leetcode/add_binary/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/add_binary/solution.py) | | 70 | [Climbing Stairs](https://github.com/wislertt/leetcode-py/blob/main/leetcode/climbing_stairs/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/climbing_stairs/solution.py) | | 75 | [Sort Colors](https://github.com/wislertt/leetcode-py/blob/main/leetcode/sort_colors/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/sort_colors/solution.py) | | 76 | [Minimum Window Substring](https://github.com/wislertt/leetcode-py/blob/main/leetcode/minimum_window_substring/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/minimum_window_substring/solution.py) | | 78 | [Subsets](https://github.com/wislertt/leetcode-py/blob/main/leetcode/subsets/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/subsets/solution.py) | | 79 | [Word Search](https://github.com/wislertt/leetcode-py/blob/main/leetcode/word_search/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/word_search/solution.py) | | 84 | [Largest Rectangle in Histogram](https://github.com/wislertt/leetcode-py/blob/main/leetcode/largest_rectangle_in_histogram/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/largest_rectangle_in_histogram/solution.py) | | 98 | [Validate Binary Search Tree](https://github.com/wislertt/leetcode-py/blob/main/leetcode/validate_binary_search_tree/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/validate_binary_search_tree/solution.py) | | 102 | [Binary Tree Level Order Traversal](https://github.com/wislertt/leetcode-py/blob/main/leetcode/binary_tree_level_order_traversal/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/binary_tree_level_order_traversal/solution.py) | | 104 | [Maximum Depth of Binary Tree](https://github.com/wislertt/leetcode-py/blob/main/leetcode/maximum_depth_of_binary_tree/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/maximum_depth_of_binary_tree/solution.py) | | 105 | [Construct Binary Tree from Preorder and Inorder Traversal](https://github.com/wislertt/leetcode-py/blob/main/leetcode/construct_binary_tree_from_preorder_and_inorder_traversal/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/construct_binary_tree_from_preorder_and_inorder_traversal/solution.py) | | 110 | [Balanced Binary Tree](https://github.com/wislertt/leetcode-py/blob/main/leetcode/balanced_binary_tree/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/balanced_binary_tree/solution.py) | | 121 | [Best Time to Buy and Sell Stock](https://github.com/wislertt/leetcode-py/blob/main/leetcode/best_time_to_buy_and_sell_stock/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/best_time_to_buy_and_sell_stock/solution.py) | | 125 | [Valid Palindrome](https://github.com/wislertt/leetcode-py/blob/main/leetcode/valid_palindrome/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/valid_palindrome/solution.py) | | 127 | [Word Ladder](https://github.com/wislertt/leetcode-py/blob/main/leetcode/word_ladder/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/word_ladder/solution.py) | | 133 | [Clone Graph](https://github.com/wislertt/leetcode-py/blob/main/leetcode/clone_graph/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/clone_graph/solution.py) | | 139 | [Word Break](https://github.com/wislertt/leetcode-py/blob/main/leetcode/word_break/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/word_break/solution.py) | | 141 | [Linked List Cycle](https://github.com/wislertt/leetcode-py/blob/main/leetcode/linked_list_cycle/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/linked_list_cycle/solution.py) | | 146 | [LRU Cache](https://github.com/wislertt/leetcode-py/blob/main/leetcode/lru_cache/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/lru_cache/solution.py) | | 150 | [Evaluate Reverse Polish Notation](https://github.com/wislertt/leetcode-py/blob/main/leetcode/evaluate_reverse_polish_notation/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/evaluate_reverse_polish_notation/solution.py) | | 155 | [Min Stack](https://github.com/wislertt/leetcode-py/blob/main/leetcode/min_stack/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/min_stack/solution.py) | | 169 | [Majority Element](https://github.com/wislertt/leetcode-py/blob/main/leetcode/majority_element/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/majority_element/solution.py) | | 199 | [Binary Tree Right Side View](https://github.com/wislertt/leetcode-py/blob/main/leetcode/binary_tree_right_side_view/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/binary_tree_right_side_view/solution.py) | | 200 | [Number of Islands](https://github.com/wislertt/leetcode-py/blob/main/leetcode/number_of_islands/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/number_of_islands/solution.py) | | 206 | [Reverse Linked List](https://github.com/wislertt/leetcode-py/blob/main/leetcode/reverse_linked_list/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/reverse_linked_list/solution.py) | | 207 | [Course Schedule](https://github.com/wislertt/leetcode-py/blob/main/leetcode/course_schedule/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/course_schedule/solution.py) | | 208 | [Implement Trie (Prefix Tree)](https://github.com/wislertt/leetcode-py/blob/main/leetcode/implement_trie_prefix_tree/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/implement_trie_prefix_tree/solution.py) | | 217 | [Contains Duplicate](https://github.com/wislertt/leetcode-py/blob/main/leetcode/contains_duplicate/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/contains_duplicate/solution.py) | | 224 | [Basic Calculator](https://github.com/wislertt/leetcode-py/blob/main/leetcode/basic_calculator/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/basic_calculator/solution.py) | | 226 | [Invert Binary Tree](https://github.com/wislertt/leetcode-py/blob/main/leetcode/invert_binary_tree/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/invert_binary_tree/solution.py) | | 230 | [Kth Smallest Element in a BST](https://github.com/wislertt/leetcode-py/blob/main/leetcode/kth_smallest_element_in_a_bst/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/kth_smallest_element_in_a_bst/solution.py) | | 232 | [Implement Queue using Stacks](https://github.com/wislertt/leetcode-py/blob/main/leetcode/implement_queue_using_stacks/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/implement_queue_using_stacks/solution.py) | | 235 | [Lowest Common Ancestor of a Binary Search Tree](https://github.com/wislertt/leetcode-py/blob/main/leetcode/lowest_common_ancestor_of_a_binary_search_tree/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/lowest_common_ancestor_of_a_binary_search_tree/solution.py) | | 236 | [Lowest Common Ancestor of a Binary Tree](https://github.com/wislertt/leetcode-py/blob/main/leetcode/lowest_common_ancestor_of_a_binary_tree/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/lowest_common_ancestor_of_a_binary_tree/solution.py) | | 238 | [Product of Array Except Self](https://github.com/wislertt/leetcode-py/blob/main/leetcode/product_of_array_except_self/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/product_of_array_except_self/solution.py) | | 242 | [Valid Anagram](https://github.com/wislertt/leetcode-py/blob/main/leetcode/valid_anagram/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/valid_anagram/solution.py) | | 278 | [First Bad Version](https://github.com/wislertt/leetcode-py/blob/main/leetcode/first_bad_version/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/first_bad_version/solution.py) | | 295 | [Find Median from Data Stream](https://github.com/wislertt/leetcode-py/blob/main/leetcode/find_median_from_data_stream/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/find_median_from_data_stream/solution.py) | | 297 | [Serialize and Deserialize Binary Tree](https://github.com/wislertt/leetcode-py/blob/main/leetcode/serialize_and_deserialize_binary_tree/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/serialize_and_deserialize_binary_tree/solution.py) | | 310 | [Minimum Height Trees](https://github.com/wislertt/leetcode-py/blob/main/leetcode/minimum_height_trees/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/minimum_height_trees/solution.py) | | 322 | [Coin Change](https://github.com/wislertt/leetcode-py/blob/main/leetcode/coin_change/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/coin_change/solution.py) | | 383 | [Ransom Note](https://github.com/wislertt/leetcode-py/blob/main/leetcode/ransom_note/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/ransom_note/solution.py) | | 409 | [Longest Palindrome](https://github.com/wislertt/leetcode-py/blob/main/leetcode/longest_palindrome/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/longest_palindrome/solution.py) | | 416 | [Partition Equal Subset Sum](https://github.com/wislertt/leetcode-py/blob/main/leetcode/partition_equal_subset_sum/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/partition_equal_subset_sum/solution.py) | | 438 | [Find All Anagrams in a String](https://github.com/wislertt/leetcode-py/blob/main/leetcode/find_all_anagrams_in_a_string/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/find_all_anagrams_in_a_string/solution.py) | | 542 | [01 Matrix](https://github.com/wislertt/leetcode-py/blob/main/leetcode/zero_one_matrix/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/zero_one_matrix/solution.py) | | 543 | [Diameter of Binary Tree](https://github.com/wislertt/leetcode-py/blob/main/leetcode/diameter_of_binary_tree/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/diameter_of_binary_tree/solution.py) | | 621 | [Task Scheduler](https://github.com/wislertt/leetcode-py/blob/main/leetcode/task_scheduler/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/task_scheduler/solution.py) | | 704 | [Binary Search](https://github.com/wislertt/leetcode-py/blob/main/leetcode/binary_search/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/binary_search/solution.py) | | 721 | [Accounts Merge](https://github.com/wislertt/leetcode-py/blob/main/leetcode/accounts_merge/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/accounts_merge/solution.py) | | 733 | [Flood Fill](https://github.com/wislertt/leetcode-py/blob/main/leetcode/flood_fill/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/flood_fill/solution.py) | | 876 | [Middle of the Linked List](https://github.com/wislertt/leetcode-py/blob/main/leetcode/middle_of_the_linked_list/README.md) | Easy | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/middle_of_the_linked_list/solution.py) | | 973 | [K Closest Points to Origin](https://github.com/wislertt/leetcode-py/blob/main/leetcode/k_closest_points_to_origin/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/k_closest_points_to_origin/solution.py) | | 981 | [Time Based Key-Value Store](https://github.com/wislertt/leetcode-py/blob/main/leetcode/time_based_key_value_store/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/time_based_key_value_store/solution.py) | | 994 | [Rotting Oranges](https://github.com/wislertt/leetcode-py/blob/main/leetcode/rotting_oranges/README.md) | Medium | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/rotting_oranges/solution.py) | | 1235 | [Maximum Profit in Job Scheduling](https://github.com/wislertt/leetcode-py/blob/main/leetcode/maximum_profit_in_job_scheduling/README.md) | Hard | [solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/maximum_profit_in_job_scheduling/solution.py) |