{ "data": { "question": { "questionId": "2157", "questionFrontendId": "2030", "boundTopicId": null, "title": "Smallest K-Length Subsequence With Occurrences of a Letter", "titleSlug": "smallest-k-length-subsequence-with-occurrences-of-a-letter", "content": "

You are given a string s, an integer k, a letter letter, and an integer repetition.

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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.

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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.

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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.

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Example 1:

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\nInput: s = "leet", k = 3, letter = "e", repetition = 1\nOutput: "eet"\nExplanation: There are four subsequences of length 3 that have the letter 'e' appear at least 1 time:\n- "lee" (from "leet")\n- "let" (from "leet")\n- "let" (from "leet")\n- "eet" (from "leet")\nThe lexicographically smallest subsequence among them is "eet".\n
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Example 2:

\n\"example-2\"\n
\nInput: s = "leetcode", k = 4, letter = "e", repetition = 2\nOutput: "ecde"\nExplanation: "ecde" is the lexicographically smallest subsequence of length 4 that has the letter "e" appear at least 2 times.\n
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Example 3:

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\nInput: s = "bb", k = 2, letter = "b", repetition = 2\nOutput: "bb"\nExplanation: "bb" is the only subsequence of length 2 that has the letter "b" appear at least 2 times.\n
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Constraints:

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Compiled with clang 11 using the latest C++ 17 standard.

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Your code is compiled with level two optimization (-O2). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.

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Most standard library headers are already included automatically for your convenience.

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OpenJDK 17 . Java 8 features such as lambda expressions and stream API can be used.

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Most standard library headers are already included automatically for your convenience.

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Python 2.7.12.

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Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.

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For Map/TreeMap data structure, you may use sortedcontainers library.

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Note that Python 2.7 will not be maintained past 2020. For the latest Python, please choose Python3 instead.

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3. Deleting an item in a hash:\\r\\n

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C# 10 with .NET 6 runtime

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Your code is compiled with debug flag enabled (/debug).

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Node.js 16.13.2.

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Ruby 3.1

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Swift 5.5.2.

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Go 1.17.6.

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Python 3.10.

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Rust 1.58.1

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With bcmath module

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