2030. Smallest K-Length Subsequence With Occurrences of a Letter
Description
You are given a string s
, an integer k
, a letter letter
, and an integer repetition
.
Return the lexicographically smallest subsequence of s
of length k
that has the letter letter
appear at least repetition
times. The test cases are generated so that the letter
appears in s
at least repetition
times.
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.
A string a
is lexicographically smaller than a string b
if in the first position where a
and b
differ, string a
has a letter that appears earlier in the alphabet than the corresponding letter in b
.
Example 1:
Input: s = "leet", k = 3, letter = "e", repetition = 1 Output: "eet" Explanation: There are four subsequences of length 3 that have the letter 'e' appear at least 1 time: - "lee" (from "leet") - "let" (from "leet") - "let" (from "leet") - "eet" (from "leet") The lexicographically smallest subsequence among them is "eet".
Example 2:
![example-2](https://spcdn.pages.dev/leetcode/problems/2030.Smallest%20K-Length%20Subsequence%20With%20Occurrences%20of%20a%20Letter/images/smallest-k-length-subsequence.png)
Input: s = "leetcode", k = 4, letter = "e", repetition = 2 Output: "ecde" Explanation: "ecde" is the lexicographically smallest subsequence of length 4 that has the letter "e" appear at least 2 times.
Example 3:
Input: s = "bb", k = 2, letter = "b", repetition = 2 Output: "bb" Explanation: "bb" is the only subsequence of length 2 that has the letter "b" appear at least 2 times.
Constraints:
1 <= repetition <= k <= s.length <= 5 * 104
s
consists of lowercase English letters.letter
is a lowercase English letter, and appears ins
at leastrepetition
times.