leetcode/work/Easy/Two Pointers/392.is-subsequence.py

"""
392. Is Subsequence
Difficulty: Easy
https://leetcode.com/problems/is-subsequence/

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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



Constraints:

        • 0 <= s.length <= 100

        • 0 <= t.length <= 10^4

        • s and t consist only of lowercase English letters.



Follow up: Suppose there are lots of incoming s, say s1, s2, ..., sk
where k >= 10^9, and you want to check one by one to see if t has its
subsequence. In this scenario, how would you change your code?
"""


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

        i, j = 0, 0
        while i < len(s) and j < len(t):
            if s[i] == t[j]:
                i += 1
            j += 1

        return i == len(s)