392. Is Subsequence

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 <= 10^4
• s and t consist only of lowercase English letters.

Complexity

• Time complexity: O(n)

• Space complexity: O(1)

Code

class Solution:
    def isSubsequence(self, s: str, t: str) -> bool:
        n, m = len(s), len(t)
        if n > m:
            return False
        if n == 0:
            return True

        j = 0

        for i in range(m):
            if j < n and s[j] == t[i]:
                j += 1

        return j == n

class Solution {
    public boolean isSubsequence(String s, String t) {
        int n = s.length();
        int m = t.length();

        if (n > m) {
            return false;
        }

        if (n == 0) {
            return true;
        }

        int j = 0;

        for (int i = 0; i < m && j < n; i++) {
            if (s.charAt(j) == t.charAt(i)) {
                j++;
            }
        }

        return j == n;
    }
}

class Solution {
public:
    bool isSubsequence(string s, string t) {
        int n = s.length();
        int m = t.length();
        int j = 0;

        for (int i = 0; i < m && j < n; i++) {
            if (s[j] == t[i]) {
                j++;
            }
        }

        return j == n;
    }
};