392. Is Subsequence Time: $O(n)$ Space: $O(1)$ C++Java 1 2 3 4 5 6 7 8 9 10 11 12 13 14class Solution { public: bool isSubsequence(string s, string t) { if (s.empty()) return true; int i = 0; for (const char c : t) if (s[i] == c && ++i == s.length()) return true; return false; } }; 1 2 3 4 5 6 7 8 9 10 11 12 13class Solution { public boolean isSubsequence(String s, String t) { if (s.isEmpty()) return true; int i = 0; for (final char c : t.toCharArray()) if (s.charAt(i) == c && ++i == s.length()) return true; return false; } }