Package g1701_1800.s1718_construct_the_lexicographically_largest_valid_sequence

Class Solution

  • public class Solution
extends Object
    1718 - Construct the Lexicographically Largest Valid Sequence.

    Medium

    Given an integer n, find a sequence that satisfies all of the following:

    • The integer 1 occurs once in the sequence.
    • Each integer between 2 and n occurs twice in the sequence.
    • For every integer i between 2 and n, the distance between the two occurrences of i is exactly i.

    The distance between two numbers on the sequence, a[i] and a[j], is the absolute difference of their indices, |j - i|.

    Return the lexicographically largest sequence_. It is guaranteed that under the given constraints, there is always a solution._

    A sequence a is lexicographically larger than a sequence b (of the same length) if in the first position where a and b differ, sequence a has a number greater than the corresponding number in b. For example, [0,1,9,0] is lexicographically larger than [0,1,5,6] because the first position they differ is at the third number, and 9 is greater than 5.

    Example 1:

    Input: n = 3

    Output: [3,1,2,3,2]

    Explanation: [2,3,2,1,3] is also a valid sequence, but [3,1,2,3,2] is the lexicographically largest valid sequence.

    Example 2:

    Input: n = 5

    Output: [5,3,1,4,3,5,2,4,2]

    Constraints:

    • 1 <= n <= 20

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • constructDistancedSequence

        public int[] constructDistancedSequence​(int n)