392. Is Subsequence

Easy
Two Pointers String Dynamic Programming

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?

func isSubsequence(s string, t string) bool {
    if len(s) == 0 {
        return true
    }
	j := 0
	for i := 0; i < len(t); i++ {
		// fmt.Println("i", string(t[i]))
		if s[j] == t[i] {
			// fmt.Println("Matched", string(t[i]), "at", i, "with", string(s[j]), "at", j)
			j++
		}
		if j >= len(s) {
			return true
		}
	}
	return false
}