The patterns behind the Blind 75.
The Blind 75 is a problem list. The patterns behind it are what actually transfer. Here is the concept-level index: 12 patterns, each mapped to the Blind 75 problems they solve.
Sliding Window
5 / 75Maintain a contiguous range and slide its boundaries to avoid recomputation.
Two Pointers
6 / 75Two cursors moving independently over a sorted or monotone structure.
Monotonic Stack
4 / 75A stack whose elements stay in non-increasing or non-decreasing order.
Prefix & Suffix
4 / 75Precompute cumulative arrays so range queries answer in O(1).
Binary Search on Answer
4 / 75When a predicate is monotonic over the answer space, binary search the answer itself.
Heap & Priority Queue
5 / 75A data structure that returns the min or max in O(log n) per operation.
Union-Find (DSU)
3 / 75A disjoint-set data structure supporting near-constant merge and find.
Topological Sort
2 / 75Linear ordering of a DAG consistent with its dependencies.
Graph BFS / DFS
10 / 75Breadth-first for shortest unweighted paths; depth-first for exhaustive traversal.
Dynamic Programming
14 / 75Break an overlapping-subproblem problem into a recurrence and cache results.
Backtracking
6 / 75DFS through a decision tree with pruning and state restoration.
Interval Sweep
4 / 75Sort events by time, sweep a line, maintain an active set for overlap questions.
A legal note
Alpha Code does not republish Blind 75 problem text. The list itself is publicly documented; we index it by pattern and point you to our own scenario variants. If you need the exact problem statements, practice them on the source platform.
Frequently asked questions
- What is the Blind 75?
- The Blind 75 is a widely-used list of 75 coding-interview problems originally curated on the LeetCode discuss forums. It's favored for being short enough to finish yet broad enough to cover most FAANG coding rounds.
- What patterns are behind the Blind 75?
- The 75 problems cluster into 12 patterns: dynamic programming (14), graph BFS/DFS (10), two pointers (6), backtracking (6), sliding window (5), heap (5), monotonic stack (4), prefix/suffix (4), binary search on answer (4), interval sweep (4), union-find (3), and topological sort (2).
- Is the Blind 75 enough to pass a FAANG interview?
- As a minimum bar, yes for many loops. As a competitive bar at Google, Meta, or Amazon for senior roles, no — you'll want the pattern fluency that comes from extending to the NeetCode 150 or to Alpha Code's full pattern library.
- Should I memorize the Blind 75 problems?
- Memorizing problem solutions is the slowest path. Learn each problem as an instance of its pattern; the pattern transfers to the 1,000 variants you'll never see on any curated list.
- What's a good alternative to the Blind 75?
- The 12-pattern alternative at /blind-75/alternative indexes the same concepts but organizes practice by pattern fluency rather than by 75 specific problems. See also /patterns for the full pattern library.
Drill patterns, not problem lists.
Start with the diagnostic. We'll show you which of the 12 patterns already transfers and which need work.