String Subsequence

Problem

Given two strings s and t, check if s is a subsequence of t. 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).

Examples

isSubsequence("ace", "abcde")
// returns true
// The string "ace" is a subsequence of "abcde"

isSubsequence("aec", "abcde")
// returns false
// The string "aec" is not a subsequence of "abcde" because
// the order of characters is changed

isSubsequence("hello", "heyllllo")
// returns true
// The string "hello" is a subsequence of "heyllllo".