Codeforces Round 921 (Div. 2)
A
We Got Everything Covered!
Codeforces
800
原题
←B →
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You are given two positive integers $n$ and $k$.

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Your task is to find a string $s$ such that all possible strings of length $n$ that can be formed using the first $k$ lowercase English alphabets occur as a subsequence of $s$.

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If there are multiple answers, print the one with the smallest length. If there are still multiple answers, you may print any of them.

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Note: A string $a$ is called a subsequence of another string $b$ if $a$ can be obtained by deleting some (possibly zero) characters from $b$ without changing the order of the remaining characters.

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Input

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The first line of input contains a single integer $t$ ($1\leq t\leq 676$) denoting the number of test cases.

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Each test case consists of a single line of input containing two integers $n$ ($1\leq n\leq 26$) and $k$ ($1\leq k\leq 26$).

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Output

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For each test case, print a single line containing a single string $s$ which satisfies the above property. If there are multiple answers, print the one with the smallest length. If there are still multiple answers, you may print any of them.

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Note

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For the first test case, there are two strings of length $1$ which can be formed using the first $2$ lowercase English alphabets, and they are present in $s$ as a subsequence as follows:

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  • $\texttt{a}: {\color{red}{\texttt{a}}}\texttt{b}$
  • $\texttt{b}: \texttt{a}{\color{red}{\texttt{b}}}$
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For the second test case, there is only one string of length $2$ which can be formed using the first lowercase English alphabet, and it is present in $s$ as a subsequence as follows:

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  • $\texttt{aa}: {\color{red}{\texttt{aa}}}$
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For the third test case, there are $4$ strings of length $2$ which can be formed using the first $2$ lowercase English alphabets, and they are present in $s$ as a subsequence as follows:

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  • $\texttt{aa}: \texttt{b}{\color{red}{\texttt{aa}}}\texttt{b}$
  • $\texttt{ab}: \texttt{ba}{\color{red}{\texttt{ab}}}$
  • $\texttt{ba}: {\color{red}{\texttt{ba}}}\texttt{ab}$
  • $\texttt{bb}: {\color{red}{\texttt{b}}}\texttt{aa}{\color{red}{\texttt{b}}}$
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For the fourth test case, there are $9$ strings of length $2$ which can be formed using the first $3$ lowercase English alphabets, and they are present in $s$ as a subsequence as follows:

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  • $\texttt{aa}: {\color{red}{\texttt{a}}}\texttt{bcb}{\color{red}{\texttt{a}}}\texttt{c}$
  • $\texttt{ab}: {\color{red}{\texttt{ab}}}\texttt{cbac}$
  • $\texttt{ac}: \texttt{abcb}{\color{red}{\texttt{ac}}}$
  • $\texttt{ba}: \texttt{abc}{\color{red}{\texttt{ba}}}\texttt{c}$
  • $\texttt{bb}: \texttt{a}{\color{red}{\texttt{b}}}\texttt{c}{\color{red}{\texttt{b}}}\texttt{ac}$
  • $\texttt{bc}: \texttt{a}{\color{red}{\texttt{bc}}}\texttt{bac}$
  • $\texttt{ca}: \texttt{ab}{\color{red}{\texttt{c}}}\texttt{b}{\color{red}{\texttt{a}}}\texttt{c}$
  • $\texttt{cb}: \texttt{ab}{\color{red}{\texttt{cb}}}\texttt{ac}$
  • $\texttt{cc}: \texttt{ab}{\color{red}{\texttt{c}}}\texttt{ba}{\color{red}{\texttt{c}}}$
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样例

Input #1
4
1 2
2 1
2 2
2 3
Output #1
ab
aa
baab
abcbac
InputCopy OutputCopy
题目信息
题号
1925A
时间限制
1 s
内存限制
256 MB
标签
构造
贪心
字符串

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