leetcode:Beautiful Arrangement II

Beautiful Arrangement II

Given two integers n and k you need to construct a list which contains n different positive integers ranging from 1 to n and obeys the following requirement:
Suppose this list is [a₁, a₂, a₃, ... , a_n], then the list [|a₁ - a₂|, |a₂ - a₃|, |a₃ - a₄|, ... , |a_n-1 - a_n|] has exactly k distinct integers.

If there are multiple answers, print any of them.

Input: n = 3, k = 1
Output: [1, 2, 3]
Explanation: The [1, 2, 3] has three different positive integers ranging from 1 to 3, and the [1, 1] has exactly 1 distinct integer: 1.

Input: n = 3, k = 2
Output: [1, 3, 2]
Explanation: The [1, 3, 2] has three different positive integers ranging from 1 to 3, and the [2, 1] has exactly 2 distinct integers: 1 and 2.

def constructArray(n, k):
    ans = list(range(1, n - k))
    for d in range(k+1):
        if d % 2 == 0:
            ans.append(n-k + d//2)
        else:
            ans.append(n - d//2)

    return ans

总结：

考虑 k = n-1的情况，[1,n,2,n-1, ... , ];

先放[1, 2, ... n-k-1],后放 [n, n-k+1, n-1, ...];

数值的除法（/）总是返回一个浮点数，要获取整数使用//操作符