g2001_2100.s2030_smallest_k_length_subsequence_with_occurrences_of_a_letter

Class Solution

java.lang.Object

g2001_2100.s2030_smallest_k_length_subsequence_with_occurrences_of_a_letter.Solution

public class Solution
extends Object

2030 - Smallest K-Length Subsequence With Occurrences of a Letter.

Hard

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 “lee**t**”)

• “let” (from “le**et**”)

• “eet” (from “l**eet**”)

The lexicographically smallest subsequence among them is “eet”.

Example 2:

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 in s at least repetition times.

Constructor Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
String	smallestSubsequence(String s, int k, char letter, int repetition)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

smallestSubsequence

public String smallestSubsequence(String s,
                                  int k,
                                  char letter,
                                  int repetition)