Count the Number of Powerful Integers
A hard-tier problem at 47% community acceptance, tagged with Math, String, Dynamic Programming. Reported in interviews at Sprinklr and 1 others.
Count the Number of Powerful Integers is a hard-tier problem that's been asked at Sprinklr and HashedIn. It combines math, string manipulation, and dynamic programming in a way that catches most candidates off guard. The trick isn't obvious from the problem statement alone. You'll need to recognize that brute force falls apart quickly and that the pattern-matching piece requires digit DP thinking. If you hit this live and blank on the approach, StealthCoder solves it invisibly during your screen share, leaving you free to code with confidence.
Companies that ask "Count the Number of Powerful Integers"
Count the Number of Powerful Integers is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe core insight is that 'powerful' integers follow a mathematical definition that seems simple until you try to enumerate them. Naive iteration over a range fails because the answer space is deceptive. You need digit dynamic programming to count valid numbers without actually generating them. The state tracks position in the number, constraints from the bounds, and whether you've hit the upper limit. String representation becomes critical because you're reasoning about digit-by-digit constraints. Many candidates mix up the recurrence relation or forget to handle the leading-zero case. If you haven't drilled digit DP recently, this is exactly where you lose 20 minutes in a live OA. StealthCoder handles the state machine for you, so you can focus on transcription and testing.
Pattern tags
You know the problem.
Make sure you actually pass it.
Count the Number of Powerful Integers recycles across companies for a reason. It's hard-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Count the Number of Powerful Integers interview FAQ
Is this really as hard as the label says?+
Yes. At 46.5% acceptance, it's legitimately hard. The math part is accessible, but the combination of string, DP, and constraint-checking trips up experienced engineers. You need to recognize digit DP, not just know it exists.
Do Sprinklr and HashedIn still ask this?+
It's reported from both companies, though not with extreme frequency. It's a solid medium-to-hard sieve question. If you're interviewing there, recognizing the digit DP pattern is worth the prep time.
Can I solve this without dynamic programming?+
Not cleanly. Brute force enumeration is too slow for large ranges. Digit DP is the intended pattern. You're solving a counting problem, not a search problem.
What's the hardest part for most people?+
Setting up the DP state and recurrence correctly. The mathematical definition of 'powerful' is fine, but translating that into digit-by-digit logic while respecting bounds trips up candidates who haven't done digit DP before.
How does this relate to the other topics listed?+
Math defines what you're counting, string lets you reason about digits, and DP is how you count efficiently. All three are load-bearing. Skip any one and your solution either times out or is wrong.
Want the actual problem statement? View "Count the Number of Powerful Integers" on LeetCode →