The core coding-round ramp: pointers and sweeps up through graphs, in the order the patterns build on each other.
Pair Sum in a Sorted Array
Algorithms & Data Structures · The two-pointer warm-up every loop still asks.
Merge Overlapping Intervals
Algorithms & Data Structures · Sort, then sweep — the pattern behind a dozen calendar problems.
Design an LRU Cache
Algorithms & Data Structures · Hash map plus doubly linked list, all operations O(1).
Course Schedule
Algorithms & Data Structures · Cycle detection dressed up as a scheduling question.
Implement debounce()
Frontend · Closures and timers, the frontend screen classic.