# [leetcode] 392. Is Subsequence _ Algorithm Problem Solve for python

## 1. Problem

392. Is Subsequence

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.

## 2. Solution

I solved this problem like this.

• Complexity
• Time complexity : O(N)
• Space complexity : O(1)
• Step
• if s len is 0, return True
• confirm s text(using s_idx) in t while for statement.
class Solution:
def isSubsequence(self, s: str, t: str) -> bool:
if not len(s):
return True

s_idx = 0
for _t in t:
if s[s_idx] == _t:
s_idx += 1
if s_idx >= len(s):
return True

return False