667. 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.

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.

Note:

1. The n and k are in the range 1 <= k < n <= 104.

 

class Solution {
public:
    vector<int> constructArray(int n, int k) {
      vector<int> vet(n);
        for (int i = 0;i < n;i++)
        {
            vet[i] = i + 1;
        }
        vector<int> vet1;
        vector<int> vet2;
        for (int i = n - k - 1;i<n ;i++)
        {
            vet1.push_back(vet[i]);
        }
        int len = vet1.size();
        int m = 0,m1 = len - 1;
        //cout << m << m1 << endl;
        bool flag = true;
        while (m <= m1)
        {
            
            if (flag == true)
            {
                vet2.push_back(vet1[m1]);
        
                m1--;
                flag = false;
            }
            else
            {
                vet2.push_back(vet1[m]);
                m++;
                flag = true;
            }
        }
    
        for (int i = n - 1 - k-1;i >=0 ;i--)
        {
            vet2.push_back(vet[i]);
        }
        return vet2;
    }
};