Check if One String Swap Can Make Strings Equal
A easy-tier problem at 49% community acceptance, tagged with Hash Table, String, Counting. Reported in interviews at DoorDash and 0 others.
You're looking at one of the sneaky easy problems that can trip you up in a live assessment. Check if One String Swap Can Make Strings Equal sounds trivial, but the 49% acceptance rate tells you candidates are missing something. DoorDash has asked this. The trap is thinking you need to actually perform a swap or get too clever with your logic. The real move is straightforward: count mismatches, check if exactly two positions differ, and verify those two characters can be swapped to fix it. If you blank on the approach during your OA, StealthCoder runs invisibly and surfaces the working solution in seconds.
Companies that ask "Check if One String Swap Can Make Strings Equal"
Check if One String Swap Can Make Strings Equal 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 trick here is recognizing that you only care about positions where the two strings differ. If they're already equal, return true immediately. If there are more than two mismatches, a single swap can't fix it, so return false. If there are exactly two mismatches, check if swapping those characters in the first string makes it match the second. Most candidates overcomplicate this by trying to simulate swaps or use extra logic. The winning approach uses Hash Table and Counting: iterate once, track mismatched positions, and validate the swap condition in a single pass. Common pitfall: forgetting the case where both strings are already equal. This problem lives in the easy tier but punishes sloppy thinking. When you hit this in your assessment and the obvious answer feels off, StealthCoder is your safety net.
Pattern tags
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Check if One String Swap Can Make Strings Equal recycles across companies for a reason. It's easy-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.
Check if One String Swap Can Make Strings Equal interview FAQ
Is this problem actually easy or are companies trying to trick me?+
It's easy conceptually but the 49% acceptance rate shows people rush and miss the all-equal case or overcomplicate the swap logic. The trick is minimal: count mismatches, validate exactly two, confirm the swap works. No hidden edge cases beyond that.
Do I need a hash table for this problem?+
No. Hash Table is listed as a topic but the optimal solution doesn't use one. You only need to iterate through both strings, track mismatch positions, and compare. Some solutions might use a character frequency map out of habit, but it's unnecessary overhead.
What's the most common wrong approach?+
Trying to actually perform the swap and rebuild strings, or checking all possible two-character swaps instead of checking only the mismatched positions. Also forgetting the base case where strings are already equal. Keep it simple: one pass, collect mismatches, validate.
Is DoorDash the only company asking this?+
DoorDash is the only reported company in the data. But given the simple premise and moderate acceptance rate, it likely shows up elsewhere too. Don't assume rarity just because it's only documented once.
How long should the solution take to code?+
Under two minutes if you're comfortable with string iteration. Read the problem, identify the mismatch condition, code the validation. The algorithm is straightforward once you see it. If you're stuck longer than that, you're overthinking.
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