leetcode

dz / leetcode

Summary

studying leetcode problems the lazy way: without coding. Instead, I'm taking a more high-level approach, writing my thoughts and intuitions on how I'd solve the, problem, then checking it with existing solutions.

Subgraphs

• 17_letter_combinations_phone_number
• 19_remove_nth_node_from_list
• 22_generate_parentheses
• 23_merge_k_sorted_lists
• 24_swap_nodes_in_pairs
• 25_reverse_nodes_in_k_group
• 31_next_permutation
• 32_longest_valid_parentheses
• 33_search_in_rotated_sorted_array
• 34_first_last_elem_sorted_array
• 39_combination_sum
• 3sum
• 41_first_missing_positive
• DP_1D
• DP_multidimensional
• add_two_numbers
• array_string
• backtracking
• binary_search
• binary_search_tree
• binary_tree_BFS
• binary_tree_DFS
• bit_manipulation
• container_with_most_water
• graphs_BFS
• graphs_DFS
• hashmap_set
• heap_priority_queue
• intervals
• linked_list
• longest_substr_no_repeats
• median_two_sorted_arrays
• monotonic_stack
• palindromic_substring
• prefix_sum
• queue
• sliding_window
• stack
• trie
• two_pointers
• two_sum

Node Tree

• leetcode75
• code_solutions
• log

Nodes

log
content	Timestamped message log from the zet.

2024-04-03 15:02:08 I'm 3 problems into my leetgrind, and I'm already seeing patterns. First, I keep reaching for brute-force solutions, which is what I was doing 2 years ago. So, my intuition hasn't really improved. Second, the solutions I'm seeing have been focused on removing the inner loop (aka not brute force). Third, hashmap has been used twice to cache previous values. Probably something I should pay attention to.

2024-04-05 15:13:28 These C++ solutions have been kinda crummy so far, and sometimes misleading. I think from now on, I'm just going to read the leetcode editorial.

2024-04-06 14:40:48 I have run out of "freebies" for editorials, which is an unfortunate discovery. I have found a workaround.

2024-04-13 15:13:25 The editorial for LC23 (merge k sorted lists) makes heavy use of built-in data structures in the Python language. Makes for practically no-code solutions for what is considered a "hard" leetcode problem. A sign that I need to think about using Python?

2024-04-15 14:23:44 noticing a lot of use of "dummy nodes" in solutions for linked list questions. My guess is that this is done to avoid null-checks in the solutions?

2024-04-24 15:20:16 A lot of what I've been thinking as "divide and conquer" really ends up being "binary search", so I think I need to look into this domain more.

leetcode75
content	Leetcode 75
hyperlink	https://leetcode.com/studyplan/leetcode-75

code_solutions
content	Code solutions (mostly C++)
parents	links/leetcode_solutions
hyperlink	https://github.com/haoel/leetcode