Palindrome Permutation
A easy-tier problem at 69% community acceptance, tagged with Hash Table, String, Bit Manipulation. Reported in interviews at Nordstrom and 2 others.
Palindrome Permutation shows up in live assessments at Google, Docusign, and Nordstrom, and 68.5% of candidates who attempt it pass. The problem asks whether a string can be rearranged into a palindrome. It's deceptively simple, and most people solve it, but the trick is knowing exactly what constraint makes a string palindrome-able. If you blank on the character-frequency logic during your OA, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Palindrome Permutation"
Palindrome Permutation 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 a palindrome has at most one character with an odd count. Most candidates either brute-force permutation generation (wrong) or overthink the problem with complex data structures. The right move is a single pass through the string, counting character frequencies or tracking parity with a hash table or bit manipulator. Hash Table and Bit Manipulation are both listed as core topics, so you might see solutions using either approach. The bit manipulation version is elegant if you're comfortable flipping bits to track odd counts. If this problem hits your live assessment and you freeze on whether multiple odd counts are allowed, StealthCoder solves it in seconds without the proctor seeing anything.
Pattern tags
You know the problem.
Make sure you actually pass it.
Palindrome Permutation 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 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.
Palindrome Permutation interview FAQ
Do I really need to generate all permutations?+
No. That's the trap. You only need to check whether a palindrome is possible, not construct it. Count character frequencies (or parity) in one pass. If at most one character has an odd count, return true. Hash Table approach is the most intuitive.
Why is Bit Manipulation listed as a topic?+
Because you can use a bitmask instead of a hash table to track odd/even counts. Flip a bit for each character you see. At the end, check if the bitmask has at most one bit set. It's elegant but not required to pass.
How much harder is this than other easy problems?+
Easier than average. The 68.5% acceptance rate confirms it's approachable. Most failures come from overthinking or misunderstanding the problem statement, not algorithmic gaps. Re-read the problem carefully before coding.
Do I need to handle uppercase, lowercase, or spaces?+
The problem statement (not in the data) usually specifies. Common variants ignore case and spaces. Check the exact problem wording on your assessment. Your hash table or bitmask doesn't care about ASCII values, so adjust your character filtering accordingly.
Why do Google, Docusign, and Nordstrom ask this?+
It tests whether you understand the mathematical property of palindromes without needing advanced data structures. It's a filter for clear thinking over algorithm memorization. These companies value candidates who can reason through constraint problems cleanly.
Want the actual problem statement? View "Palindrome Permutation" on LeetCode →