Shifting Letters II
A medium-tier problem at 53% community acceptance, tagged with Array, String, Prefix Sum. Reported in interviews at Veritas and 0 others.
Shifting Letters II is a medium-difficulty problem that Veritas has asked. You're given a string and a list of range-based shift operations, and you need to figure out the final string after applying all shifts. The naive approach, simulating each shift operation individually, will time out on larger inputs. The trick is recognizing this as a prefix-sum problem in disguise. Instead of actually shifting characters repeatedly, you calculate the net shift value for each position once, then apply all shifts in a single pass. It's the kind of problem where the pattern clicks once you see it, but it's easy to miss under time pressure. If this hits your live OA and you blank on the prefix-sum angle, StealthCoder surfaces a working solution in seconds.
Companies that ask "Shifting Letters II"
Shifting Letters II 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 by a senior engineer who knows the OA is theater. This is the script.
Get StealthCoderThe core challenge is that naive simulation is O(n*m) where n is the string length and m is the number of operations. You'll get TLE. The insight is to build a difference array that tracks shift direction changes at each boundary. At every position, you accumulate the net shift amount using a running sum, then apply it to the character. This reduces complexity to O(n+m). Common pitfalls include forgetting to handle the last position's accumulated shift, confusing shift direction (forward vs backward), or trying to mutate the string while iterating. The Array and Prefix Sum topics are exactly what you need here. StealthCoder is your safety net if the prefix-sum pattern doesn't materialize during the assessment.
Pattern tags
You know the problem.
Make sure you actually pass it.
Shifting Letters II recycles across companies for a reason. It's medium-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 by a senior engineer who knows the OA is theater. This is the script. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Shifting Letters II interview FAQ
Is this problem still asked at FAANG or only at smaller companies?+
The input data shows Veritas asked it. It's a medium-difficulty problem with 53% acceptance, which means it's selective enough to appear in real interviews but not so hard it's only at top-tier companies. The prefix-sum pattern itself is universally relevant.
What's the actual trick I'm missing if I time out?+
You're probably simulating each shift operation on the string directly. Instead, build a difference array to track shift deltas at range boundaries, then walk through once with a running sum to apply net shifts per position. This is classic prefix-sum pattern, O(n+m) instead of O(n*m).
How does this relate to classic Prefix Sum problems?+
Standard prefix-sum aggregates values over a range. Here you're using the same idea but for shift operations. The difference array technique lets you record range updates in O(1) and resolve them in O(n). It's the same principle, different domain.
What traps do most candidates fall into?+
Forgetting to handle character wrapping (z shifts to a, not beyond), losing track of accumulated shift values, and mutating the string in place while calculating. Build a result array and index carefully to avoid off-by-one errors on range boundaries.
How much time should I spend on this in an interview?+
The naive solution is fast to code but wrong. Recognizing the prefix-sum pattern should take 5-10 minutes if you've seen it before. If you haven't, the pattern is learnable in real time. The implementation itself is usually under 15 minutes once you have the approach locked.
Want the actual problem statement? View "Shifting Letters II" on LeetCode →