isSubsequence.py

"""
Given two strings s and t, return true if s is a subsequence of t, or false otherwise.

A subsequence of a string is a new string that is formed from the original string by deleting some (can be none) of the
characters without disturbing the relative positions of the remaining characters.
(i.e., "ace" is a subsequence of "abcde" while "aec" is not).

Example 1:
Input: s = "abc", t = "ahbgdc"
Output: true

Example 2:
Input: s = "axc", t = "ahbgdc"
Output: false

"""


class Solution:
    def isSubsequence(self, s: str, t: str) -> bool:
        if len(s) > len(t):
            return False
        if s == t or len(s) == 0:
            return True

        i = j = 0

        while i < len(t) and j < len(s):
            if t[i] == s[j]:
                j += 1
            i += 1
            if j == len(s):
                return True
        return False