Just finished a session with a trainee Snowflake The only two words I can think of are: "Against All Odds". In the past, we all think Snowflake OA is not too difficult, just write it and you can AC it, but this time is different, Q2 took me 80 lines to pass, and Q3 even made me doubt my life. Is this really the Snowflake I know so well? Luckily, I managed to get all three questions AC, so let's talk about it in detail.
Q1: Simple Array Rotation Game
Problem:
You are given an array of distinct positive integers and a list of left rotation counts. For each rotation, you need to determine the index of the maximum element after performing the rotation.
Solution Idea:
This is actually a warm-up problem. First, find the subscript i of the largest element, and after each left shift of k bits, its position is:
new_index = (i - k % n + n) % n
Simple seconds.
Q2: Minimum Height
Problem:
You are given a rooted tree with tree_nodes nodes (root = 1). You can perform at most max_operations operations. Each operation lets you cut an edge (u, v) where v is the parent of u, and attach u (with its subtree) directly under the root. The goal is to minimize the tree height.
Solution Idea:
This question is hardcore.
- Run the DFS program first to make it easier to maintain the subtree information.
- expense or outlay binary search Dichotomize answer h and then do feasibility check.
- Greedy from high to low depth, and if the maximum depth of a subtree == h, force a break and hook it to the root.
- Maintain coverage intervals with Fenwick Tree / BIT to ensure manageable complexity.
It took me about 80 lines of code to get through it, definitely not at the regular OA level.
Q3: Infinite Rotation
Problem:
There are n points on a 2D plane. I constantly moves towards point i+1The question is whether all points will eventually meet at a single location.
Solution Idea:
- For n = 2, it must meet.
- For n = 3, this works only when equilateral triangles are involved.
- For n = 4, it must be square.
What it boils down to is this: the only way to finally meet is to form a positive polygon at the originating point.
Judgment conditions:
- All neighboring points have equal side lengths;
- The dot product and fork product of neighboring vectors agree;
- Special judgment collinear (co-linear) cases.
This is like a geometry simulation, but in fact, there are many hidden cases, and I had to print cases like crazy to get through it, and then I finally got to the AC.
Snowflake OA - Frequently Asked Questions FAQ
Q1: How does the difficulty of Snowflake OA compare to other big manufacturers?
A: This time, the difficulty level is significantly higher, Q2/Q3 is completely close to onsite level, which is a bit more hardcore than normal Meta and Google OA.
Q2: Is there enough time?
A: 120 minutes for 3 questions is actually quite tight. 10 minutes is recommended for Q1, at least 40 minutes should be reserved for Q2, and Q3 may require crazy debugging of hidden cases.
Q3: Are the questions high frequency?
A: Q1 is a high-frequency array rotation problem, Q2 is cold but examines the comprehensive ability of tree+data structure, Q3 is a variant of the classic mice problem, and Snowflake is obviously raising the difficulty this time.
Q4: What should I do if I am stuck in the hidden case?
A: Since the platform has a limited number of commits, it's best to use print to debug small samples and get closer to the bugs. programhelp can provide remote voice assistance in these scenarios to help you find the breakthrough quickly.
Q5: Any advice on preparing for the exam?
A.
- Brush up on some tree related questions ahead of time, and be proficient in DFS sequences/bisections/data structures;
- Do a few more geometry problems to familiarize yourself with how to determine dot products and fork products;
- Practice at least two sets of problems on CodeSignal to familiarize yourself with the platform environment.
OA three questions all AC, to help you less
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