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 <= 104
s and t consist only of lowercase English letters.
Follow up: Suppose there are lots of incoming s, say s1, s2, …, sk where k >= 109, and you want to check one by one to see if t has its subsequence. In this scenario, how would you change your code?
- code
class Solution {
public boolean isSubsequence(String s, String t) {
int si = 0, ti = 0;
while (si < s.length() && ti < t.length()){
if (s.charAt(si) == t.charAt(ti)) si++;
ti++;
}
return si == s.length();
}
}
- code
class Solution {
public boolean isSubsequence(String s, String t) {
int si = 0, ti = 0;
while (si < s.length()){
while(ti < t.length() && s.charAt(si) != t.charAt(ti)){
ti++;
}
if (ti < t.length() && s.charAt(si) == t.charAt(ti)){
si++;
ti++;
}else{
return false;
}
}
return si == s.length();
}
}
- code
class Solution:
def isSubsequence(self, s: str, t: str) -> bool:
si = ti = 0
while si < len(s) and ti < len(t):
if s[si] == t[ti]:
si += 1
ti += 1
if si == len(s): return True
return False