What the Course Schedule problem is actually testing
6 min read Course Schedule and its harder sibling are dressed-up cycle detection on a directed graph, and there are two clean ways to handle both. Read article
Coding Interview Questions
Coding Interview Questions
The sort-then-sweep trick behind merge intervals
6 min read How sorting by start time turns merge intervals, insert interval, and meeting rooms into one linear sweep. Read article
Coding Interview Questions
Trapping Rain Water, from brute force to two pointers
6 min read The trapped-water problem has three standard solutions, and the gap between them is what an interviewer is actually grading. Read article
Coding Interview Questions
Two Sum, and the hash-map habit it’s really testing
6 min read Two Sum looks trivial, but the jump from the brute-force pair check to the one-pass hash map is the exact skill interviewers are screening for. Read article
Coding Interview Questions
The 15 coding patterns that cover most interview problems
7 min read A reference table mapping fifteen coding-interview patterns to the signal that triggers each one and the canonical problem to learn it on. Read article
Dynamic Programming
0/1 Knapsack Problem: DP Solution with Space Optimization
3 min read The 0/1 Knapsack problem is one of the most important DP patterns. Unlike coin change (unbounded knapsack), each item can Read article
Dynamic Programming
Coin Change: Bottom-Up and Top-Down Dynamic Programming
2 min read Coin Change (LeetCode 322) is the canonical dynamic programming problem. It tests your ability to identify optimal substructure, choose between Read article
