Palindrome
A palindrome reads the same forward and backward after applying the problem's normalization rules.
이 멘탈 모델부터 시작하세요
A palindrome reads the same forward and backward after applying the problem's normalization rules.
불필요한 전문용어 없이 동작 방식 이해하기
Two pointers can compare characters from both ends in O(n) time and O(1) extra space if normalization is done in-place/logically.
Always clarify whether spaces, punctuation and letter case should be ignored.
알고리즘을 연속된 의사결정으로 읽기
Clarify Unicode/case/normalization assumptions.
Define indexes or prefix state.
Reuse previously learned match information when the algorithm allows it.
Read a tiny input by hand and write down the state after every important operation. For Palindrome, the goal is to make the invariant visible rather than to memorize code.
function isPalindrome(text) {
const s = text.toLowerCase().replace(/[^a-z0-9]/g, "");
let l = 0, r = s.length - 1;
while (l < r) {
if (s[l++] !== s[r--]) return false;
}
return true;
}문법을 외우지 마세요. 각 줄에서 바뀌는 상태를 따라가고 위에서 설명한 불변식과 연결하세요.
Varies by implementation / input constraints
Do not quote this complexity mechanically. Ask which operation or input dimension it describes, then derive the cost from the loops, recursion depth, data-structure operations and any preprocessing assumptions.
적합한 경우
- Use specialized matching algorithms when repeated or large-string searching makes naive scanning too expensive.
보통 어디에서 문제가 생기는가
- Ignoring Unicode semantics.
- Confusing substring with subsequence.
- Off-by-one prefix/index bugs.
전문적인 답변 구조
Clarify input rules first; many wrong solutions solve a different normalization problem than the interviewer asked.
What problem does Palindrome solve?
A palindrome reads the same forward and backward after applying the problem's normalization rules.
복잡도에 대해 무엇을 언급해야 하나요?
Its typical cost here is Varies by implementation / input constraints, but a complete answer should connect that cost to the representation, input constraints and the dominant operations.
가장 흔한 실수는 무엇인가요?
Ignoring Unicode semantics.