392. Is Subsequence
1. Description
Given a string s and a string t, check if s is subsequence of t.
A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (ie, “ace” is a subsequence of “abcde” while “aec” is not).
2. Example
Example 1:
Input: s = “abc”, t = “ahbgdc”
Output: true
Example 2:
Input: s = “axc”, t = “ahbgdc”
Output: false
3. Constraints
- 0 <= s.length <= 100
- 0 <= t.length <= $10^4$
- Both strings consists only of lowercase characters.
4. Solutions
Two Pointers
n = target.size()
Time complexity: O(n)
Space complexity: O(1)
class Solution {
public:
bool isSubsequence(const string &sub, const string &target) {
int sub_index = 0;
for (int i = 0; i < target.size() && sub_index < sub.size(); ++i) {
if (sub[sub_index] == target[i]) {
++sub_index;
}
}
return sub_index == sub.size();
}
};