Skip to content

667. Beautiful Arrangement II

Difficulty Topics

Description

Given two integers n and k, construct a list answer that contains n different positive integers ranging from 1 to n and obeys the following requirement:

  • Suppose this list is answer = [a1, a2, a3, ... , an], then the list [|a1 - a2|, |a2 - a3|, |a3 - a4|, ... , |an-1 - an|] has exactly k distinct integers.

Return the list answer. If there multiple valid answers, return any of them.

 

Example 1:

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

Example 2:

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.

 

Constraints:

  • 1 <= k < n <= 104

Solution

beautiful-arrangement-ii.py
class Solution:
    def constructArray(self, n: int, k: int) -> List[int]:
        res = []

        i, j = 1, n

        for _ in range(n):
            if k % 2 == 0:
                res.append(i)
                i += 1
            else:
                res.append(j)
                j -= 1

            if k > 1:
                k -= 1

        return res