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, ... , an], then the list [|a1 - a2|, |a2 - a3|, |a3 - a4|, ... , |an-1 - an|] 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