CF1701B.Permutation

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题目描述

Recall that a permutation of length nn is an array where each element from 11 to nn occurs exactly once.

For a fixed positive integer dd , let's define the cost of the permutation pp of length nn as the number of indices ii (1i<n)(1 \le i < n) such that pid=pi+1p_i \cdot d = p_{i + 1} .

For example, if d=3d = 3 and p=[5,2,6,7,1,3,4]p = [5, 2, 6, 7, 1, 3, 4] , then the cost of such a permutation is 22 , because p23=p3p_2 \cdot 3 = p_3 and p53=p6p_5 \cdot 3 = p_6 .

Your task is the following one: for a given value nn , find the permutation of length nn and the value dd with maximum possible cost (over all ways to choose the permutation and dd ). If there are multiple answers, then print any of them.

输入格式

The first line contains a single integer tt ( 1t5001 \le t \le 500 ) — the number of test cases.

The single line of each test case contains a single integer nn ( 2n21052 \le n \le 2 \cdot 10^5 ).

The sum of nn over all test cases does not exceed 21052 \cdot 10^5 .

输出格式

For each test case, print the value dd in the first line, and nn integers in the second line — the permutation itself. If there are multiple answers, then print any of them.

输入输出样例

  • 输入#1

    2
    2
    3

    输出#1

    2
    1 2
    3
    2 1 3
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