Maximum length prefix of one string that occurs as subsequence in another

Given two strings s and t. The task is to find maximum length of some prefix of the string S which occur in string t as subsequence.
Examples : 
 

Input : s = "digger"
              t = "biggerdiagram"
Output : 3
digger
biggerdiagram
Prefix "dig" of s is longest subsequence in t.

Input : s = "geeksforgeeks"
              t = "agbcedfeitk"
Output : 4

A simple solutions is to consider all prefixes on by one and check if current prefix of s[] is a subsequence of t[] or not. Finally return length of the largest prefix.

An efficient solution is based on the fact that to find a prefix of length n, we must first find the prefix of length n – 1 and then look for s[n-1] in t. Similarly, to find a prefix of length n – 1, we must first find the prefix of length n – 2 and then look for s[n – 2] and so on. 

Maximum length prefix of one string that occurs as subsequence in another: https://www.geeksforgeeks.org/maximum-length-prefix-one-string-occurs-subsequence-another/