When i click on Snowflake At the moment when OA linked, I actually felt a little unsure. There are 3 questions in 90 minutes. The description of the second question is two and a half paragraphs. The third question is a typical DP optimization question. The time is tight and there are many boundaries. The pressure is much greater than I expected. In the end, I passed them all. This time I compiled the real high-frequency question types, complete problem-solving ideas and code templates I encountered. I hope it can help students who are preparing for Snowflake and avoid pitfalls.
Snowflake OA overall situation
- Platform:HackerRank
- Duration:90 minutes
- Question volume: 3 Coding questions
- Difficulty：Easy-Medium + Medium + Medium-Hard
- Core inspection: Dynamic programming, string processing, greedy algorithm, boundary case processing
Snowflake OA is characterized by long title descriptions, harsh boundary conditions, and high time pressure. Below are some of the most frequently asked questions in 2025-2026.
Detailed explanation of high-frequency real questions (with ideas + code)
1. Prime String Partition (extremely high frequency · DP)
Topic: Given a string s consisting only of numbers, split it into multiple substrings. The number represented by each substring is a prime number without leading zeros. Find the total number of different splitting schemes (the result is modulo 10^9 + 7).
Problem-solving ideas:
- Preprocess all possible prime numbers (sieve method)
- Use DP: dp[i] represents the number of legal division schemes that can be formed by the first i characters
- For each position i, enumerate possible split starting points j and check whether the substring s[j:i] is a prime number
- Be careful to avoid leading zeros (length >1 cannot start with ‘0’)
Def waysToPartition(s: str) -> int:
MOD = 10**9 + 7
n = len(s)
is_prime = [False] * (n + 1)
for i in range(2, n + 1):
if all(i % j != 0 for j in range(2, int(i**0.5) + 1)):
is_prime[i] = True
dp = [0] * (n + 1)
dp[0] = 1
for i in range(1, n + 1):
for j in range(i):
if s[j] == '0' and i - j > 1:
continue
num = int(s[j:i])
if num <= n and is_prime[num]:
dp[i] = (dp[i] + dp[j]) % MOD
return dp[n]2. Text Scoring / Prefix Match Score (high frequency · string)
Topic: Given two strings text and pattern, calculate the prefix matching score with pattern for each position in text (taking into account the overlap of prefixes and suffixes), and return the total score.
Problem-solving ideas:
- Calculate the longest matching prefix length for each position using double pointers or KMP algorithm
- Accumulate points according to rules
- Need to pay attention to boundaries and overlaps
Core skills: KMP's next array can significantly optimize the matching process.
3. Vowel Limit / Constrained Vowel Strings (High Frequency·DP)
Topic: Given the word length n and the maximum number of consecutive vowels k, find how many legal strings that meet the conditions that can be formed using lowercase letters (modulo 10^9+7).
Problem-solving ideas:
- DP state design: dp[i][j] represents the number of legal strings with length i and current number of consecutive vowels j
- Transfer: j is reset to 0 when the current letter is a consonant, and is incremented when it is a vowel.
- Note that state compression optimizes space
Def countVowelStrings(n: int, k: int) -> int:
MOD = 10**9 + 7
dp = [[0] * (k + 1) for _ in range(n + 1)]
dp[0][0] = 1
for i in range(1, n + 1):
for j in range(k + 1):
# is currently a consonant
dp[i][0] = (dp[i][0] + sum(dp[i-1])) % MOD
# is currently a vowel
if j > 0:
dp[i][j] = (dp[i][j] + dp[i-1][j-1] * 5) % MOD
return sum(dp[n]) % MOD4. Task Scheduling with Constraints (medium and high frequency · greedy/priority queue)
Topic: Given the start time, end time and priority of a series of tasks, find the maximum number of tasks that can be executed simultaneously, or the minimum number of machines required.
Problem-solving ideas:
- Classic greedy: Sort by end time, use priority queue to maintain the end time of currently executing tasks
- Every time a new task arrives, the completed task pops up
5. String Transformation / Rotation Check (IF)
Topic: Determine whether the string src can obtain the target through several rotation operations, and find the minimum number of rotations (return -1 if impossible).
Problem-solving ideas:
- If the length is different, -1 is returned directly.
- Classic technique: target in (src + src)
Tips for preparing for war
- DP is the absolute focus: It is recommended to brush at least 15-20 DP questions, especially counting and state compression DP
- Time management: The first question is limited to 20 minutes, the second question is 25-30 minutes, and the third question ensures that the correct framework and major optimizations are written.
- Coding habits: Boundary cases (empty string, single character, identical characters, etc.) must be processed completely
- Practice method: HackerRank Strict 90-minute full-scale simulation + LeetCode DP/String topic
A more efficient way to prepare for OA than LeetCode
When I was preparing for Snowflake OA, I referred to a lot of real interviews and high-frequency question banks compiled by Programhelp. Also, they also provide OA practical simulation, Mock Interview, Real-time voice assistance , as well as high-frequency question trend updates. We have helped many students get on board and are preparing to be approached by other companies. Many students have received offers from FAANG. If you are also preparing for OA or interviews, you might as well learn about it, it is much more efficient than just answering questions on your own.
