Coding Practice Bank

A themed set of the string problems that show up first in almost every technical interview — reversing, palindrome checks, anagram checks, and sliding-window substring problems — taught through the reasoning that gets you to an optimal solution, not just the final code.

A themed set of classic array and matrix problems — two-sum, Kadane's maximum subarray, in-place rotation, the missing-number trick, and matrix transposition and spiral traversal — built around the recurring idea of trading a second pass or extra memory for a single, tighter pass.

A themed set of classic recursion and backtracking problems — factorial and Fibonacci as the gateway into exponential blowup, then subsets, permutations, N-Queens, and a simplified Sudoku solver as progressively deeper applications of the 'choose, explore, un-choose' backtracking template.

A themed set of classic dynamic programming problems — climbing stairs, 0/1 knapsack, longest common subsequence, coin change, and longest increasing subsequence — each one taught explicitly through the recursion-to-memoization-to-tabulation progression, so the transition from 'it works but it's slow' to 'it's fast' is never a magic trick.

A themed set of classic linked-list and binary-tree problems — reversing a list, Floyd's cycle detection, the middle-of-list two-pointer trick, BFS level-order traversal, BST validation, and lowest common ancestor — all built around pointer manipulation and the two-pointer/traversal techniques that make these structures tractable without extra memory.

A themed set of classic sorting, searching, and graph problems — a from-scratch divide-and-conquer sort, binary search and its off-by-one traps, binary search on a rotated array, BFS versus DFS graph traversal, and directed-cycle detection — closing out the coding practice bank with the algorithmic building blocks almost every harder interview question is assembled from.