AtCoder Regular Contest 144
C
K Derangement
AtCoder
⌀ 1622
原题
← BD →
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Problem Statement

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You are given positive integers $N$ and $K$. Find the lexicographically smallest permutation $A = (A_1, A_2, \ldots, A_N)$ of the integers from $1$ through $N$ that satisfies the following condition:

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  • $\lvert A_i - i\rvert \geq K$ for all $i$ ($1\leq i\leq N$).
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If there is no such permutation, print -1.

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What is lexicographical order on sequences? The following is an algorithm to determine the lexicographical order between different sequences $S$ and $T$. Below, let $S_i$ denote the $i$-th element of $S$. Also, if $S$ is lexicographically smaller than $T$, we will denote that fact as $S \lt T$; if $S$ is lexicographically larger than $T$, we will denote that fact as $S \gt T$. Let $L$ be the smaller of the lengths of $S$ and $T$. For each $i=1,2,\dots,L$, we check whether $S_i$ and $T_i$ are the same. If there is an $i$ such that $S_i \neq T_i$, let $j$ be the smallest such $i$. Then, we compare $S_j$ and $T_j$. If $S_j$ is less than $T_j$ (as a number), we determine that $S \lt T$ and quit; if $S_j$ is greater than $T_j$, we determine that $S \gt T$ and quit. If there is no $i$ such that $S_i \neq T_i$, we compare the lengths of $S$ and $T$. If $S$ is shorter than $T$, we determine that $S \lt T$ and quit; if $S$ is longer than $T$, we determine that $S \gt T$ and quit.

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Constraints

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  • $2\leq N\leq 3\times 10^5$
  • $1\leq K\leq N - 1$
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Input

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Input is given from Standard Input in the following format:

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N K

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Output

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Print the lexicographically smallest permutation $A = (A_1, A_2, \ldots, A_N)$ of the integers from $1$ through $N$ that satisfies the condition, in the following format:

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A_1 A_2 \ldots A_N

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If there is no such permutation, print -1.

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样例

Input #1
3 1
Output #1
2 3 1
Two permutations satisfy the condition: $(2, 3, 1)$ and $(3, 1, 2)$. For instance, the following holds for $(2, 3, 1)$: - $\lvert A_1 - 1\rvert = 1 \geq K$ - $\lvert A_2 - 2\rvert = 1 \geq K$ - $\lvert A_3 - 3\rvert = 2 \geq K$
Input #2
8 3
Output #2
4 5 6 7 8 1 2 3
Input #3
8 6
Output #3
-1
题目信息
题号
arc144_c
时间限制
2 s
内存限制
1024 MB

题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。