Archived LeetCode practice notes.
11 items
Older practice notes organized by problem range.
LeetCode practice notes for problems 1 through 99, including A clear explanation of the Two Sum problem using brute force first, then an optimized hash map solution.
LeetCode practice notes for problems 100 through 199, including A detailed guide to solving Same Tree with recursive DFS and structural comparison.
LeetCode practice notes for problems 200 through 299, including A clear explanation of counting connected groups of land cells in a grid using DFS or BFS.
LeetCode practice notes for problems 300 through 399, including A dynamic programming and patience sorting solution for finding the longest strictly increasing subsequence in an array.
LeetCode practice notes for problems 400 through 499, including A clear explanation of finding the nth digit in the infinite integer sequence using digit groups and arithmetic.
LeetCode practice notes for problems 500 through 599, including A clear explanation of filtering words that can be typed using only one row of an American keyboard.
LeetCode practice notes for problems 600 through 699, including A clear digit dynamic programming solution for counting numbers whose binary representation does not contain consecutive ones.
LeetCode practice notes for problems 700 through 799, including Search for a target value in a binary search tree and return the subtree rooted at the matching node.
LeetCode practice notes for problems 800 through 899, including A clear explanation of finding the closest shorthand RGB color by rounding each color channel to the nearest repeated hexadecimal pair.
LeetCode practice notes for problems 900 through 999, including A clear explanation of designing an iterator over a run-length encoded sequence without expanding it.
LeetCode practice notes for problems 1000 through 1100, covering interval DP, sliding window, binary search, greedy, SQL, and more.