Is Subsequence

EasyTwo Pointerstwo pointers

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

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Problem

Given two strings s and t, decide whether s is a subsequence of t. A subsequence is formed by deleting zero or more characters from t without changing the order of the characters that remain. Return true if s can be obtained this way, otherwise false. The empty string is a subsequence of every string. Target O(|t|) time.

Examples

Input: s = "ace", t = "abcde"
Output: true
Keep a, c and e from "abcde" and delete the rest.
Input: s = "aec", t = "abcde"
Output: false
In t, c appears before e, so the order "a, e, c" cannot be kept.

Constraints

  • 0 <= s.length <= 100
  • 0 <= t.length <= 10^4
  • s and t consist of lowercase English letters

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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