2486. Append Characters to String to Make Subsequence
Medium
You are given two strings s and t consisting of only lowercase English letters.
Return the minimum number of characters that need to be appended to the end of s so that t becomes a subsequence of s.
A subsequence is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.
Example 1:
- Input: s = “coaching”, t = “coding”
- Output: 4
-
Explanation: Append the characters “ding” to the end of s so that s = “coachingding”.
Now, t is a subsequence of s (“coaching*ding*”).
It can be shown that appending any 3 characters to the end of s will never make t a subsequence.
Example 2:
- Input: s = “abcde”, t = “a”
- Output: 0
- Explanation: t is already a subsequence of s (“abcde”).
Example 3:
- Input: s = “z”, t = “abcde”
- Output: 5
-
Explanation: Append the characters “abcde” to the end of s so that s = “zabcde”.
Now, t is a subsequence of s (“z*abcde*”).
It can be shown that appending any 4 characters to the end of s will never make t a subsequence.
Constraints:
1 <= s.length, t.length <= 105-
sandtconsist only of lowercase English letters.
Solution:
class Solution {
/**
* @param String $s
* @param String $t
* @return Integer
*/
function appendCharacters($s, $t) {
$i = 0;
foreach(str_split($s) as $c) {
if ($c == $t[$i]) {
if (++$i == strlen($t)) {
return 0;
}
}
}
return strlen($t) - $i;
}
}
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