题目描述
Problem Statement
The happiness of $a permutation P=(P_1,P_2,\ldots,P_N)$ of $(1,\dots,N)$ is defined as follows.
- Let $A=(A_1,A_2,\ldots,A_{N-1})$ be a sequence of length N-1 with $A_i = |P_i-P_{i+1}|(1\leq i \leq N-1)$. The happiness of P is the length of a longest strictly increasing subsequence of A.
Print a permutation P such that P_1 = X with the greatest happiness.
Input
Input is given from Standard Input in the following format:
N X
Output
Print a permutation P such that P_1 = X with the greatest happiness, in the following format:
$P_1 P_2 \ldots P_N$
If there are multiple solutions, printing any of them will be accepted.
Constraints
- $2 \leq N \leq 2\times 10^5$
- $1 \leq X \leq N$
- All values in input are integers.
Sample Input 1
3 2
Sample Output 1
2 1 3
Since A=(1,2), the happiness of P is 2, which is the greatest happiness achievable, so the output meets the requirement.
Sample Input 2
3 1
Sample Output 2
1 2 3
Since A=(1,1), the happiness of P is 1, which is the greatest happiness achievable, so the output meets the requirement.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分