leetcode/apps/docs/content/(two-pointers)/392-is-subsequence.mdx

---
title: '392. Is Subsequence'
description: Given two strings s and t, return true if s is a subsequence of t, or false otherwise
sidebar:
  label: 'Is Subsequence'
  badge: 'Easy'
---

<Badge variant="accent">Two Pointers</Badge>

::::warning
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?
::::

### 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.

## Solution

```py
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)
```