Problem
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).
Algorithm
Use two pointers to follow the two strings.
Code
python3
class Solution:
def isSubsequence(self, s: str, t: str) -> bool:
sIndex, tIndex, sLen, tLen = 0, 0, len(s), len(t)
while sIndex < sLen and tIndex < tLen:
if s[sIndex] == t[tIndex]:
sIndex += 1
tIndex += 1
else:
tIndex += 1
return sIndex >= sLen