Here, We see Beautiful Arrangement II LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

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Beautiful Arrangement II LeetCode Solution

Problem Statement

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, … , a_n], then the list [|a₁ – a₂|, |a₂ – a₃|, |a₃ – a₄|, … , |a_n-1 – a_n|] 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.

Beautiful Arrangement II Solution C++

class Solution {
public:
    vector<int> constructArray(int n, int k) {
        int diff = n - k;
        int lo = 1;
        int hi = n;
        vector<int> out;
        int i = 0;
        while(i < diff){
            out.push_back(lo);
            lo++;
            i++;
        }
        bool flag = true;
        for(int i = out.size()   ; i < n ; i++){
		   if(flag){
                out.push_back(hi);
                hi--;
                flag = false;
            }
            else{
                out.push_back(lo);
                lo++;
                flag = true;
            }
        }
        return out;
    }
};Code language: PHP (php)

Beautiful Arrangement II Solution Java

class Solution {
    public int[] constructArray(int n, int k) {
        int diff = n - k;
        int lo = 1;
        int hi = n;
        int[] out = new int[n];
        int i = 0;
        while(i < diff){
            out[i] = lo;
            lo++;
            i++;
        }
        boolean flag = true;
        for( ; i < n ; i++){
            if(flag){
                out[i] = hi;
                hi--;
                flag = false;
            }
            else{
                out[i] = lo;
                lo++;
                flag = true;
            }
        }
        return out;
    }
}Code language: PHP (php)

Beautiful Arrangement II Solution JavaScript

var constructArray = function(n, k) {
    let ans = new Array(n)
    for (let i = 0, a = 1, z = k + 1; i <= k; i++)
        ans[i] = i % 2 ? z-- : a++
    for (let i = k + 1; i < n;)
        ans[i] = ++i
    return ans
};Code language: JavaScript (javascript)

Beautiful Arrangement II Solution Python

class Solution(object):
    def constructArray(self, n, k):
        ans, a, z = [0] * n, 1, k + 1
        for i in range(k+1):
            if i % 2:
                ans[i] = z
                z -= 1
            else:
                ans[i] = a
                a += 1
        for i in range(k+1,n):
            ans[i] = i + 1
        return ans