LeetCode_392. Is Subsequence

392. Is Subsequence

Easy

Given a string s and a string t, check if s is subsequence of t.

You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) string, and s is a short string (<=100).

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).

Example 1:
s = "abc", t = "ahbgdc"

Return true.

Example 2:
s = "axc", t = "ahbgdc"

Return false.

Follow up:
If there are lots of incoming S, say S1, S2, ... , Sk where k >= 1B, and you want to check one by one to see if T has its subsequence. In this scenario, how would you change your code?

Credits:
Special thanks to @pbrother for adding this problem and creating all test cases.

package leetcode.easy;
 
public class IsSubsequence {
	public boolean isSubsequence(String s, String t) {
		int i = 0;
		int j = 0;
		for (; i < s.length() && j < t.length();) {
			if (s.charAt(i) == t.charAt(j)) {
				i++;
				j++;
			} else {
				j++;
			}
		}
		if (i == s.length()) {
			return true;
		} else {
			return false;
		}
	}
 
	@org.junit.Test
	public void test() {
		System.out.println(isSubsequence("abc", "ahbgdc"));
		System.out.println(isSubsequence("axc", "ahbgdc"));
	}
}