LeetCode 0667. Beautiful Arrangement II Solution in Java, Python, C++, JavaScript, Go & Rust | Explanation + Code

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

Solutions

Solution 1

PythonJavaC++GoTypeScript

class Solution: def constructArray(self, n: int, k: int) -> List[int]: l, r = 1, n ans = [] for i in range(k): if i % 2 == 0: ans.append(l) l += 1 else: ans.append(r) r -= 1 for i in range(k, n): if k % 2 == 0: ans.append(r) r -= 1 else: ans.append(l) l += 1 return ans(code-box)

class Solution { public int[] constructArray(int n, int k) { int l = 1, r = n; int[] ans = new int[n]; for (int i = 0; i < k; ++i) { ans[i] = i % 2 == 0 ? l++ : r--; } for (int i = k; i < n; ++i) { ans[i] = k % 2 == 0 ? r-- : l++; } return ans; } }(code-box)

class Solution { public: vector<int> constructArray(int n, int k) { int l = 1, r = n; vector<int> ans(n); for (int i = 0; i < k; ++i) { ans[i] = i % 2 == 0 ? l++ : r--; } for (int i = k; i < n; ++i) { ans[i] = k % 2 == 0 ? r-- : l++; } return ans; } };(code-box)

func constructArray(n int, k int) []int { l, r := 1, n ans := make([]int, n) for i := 0; i < k; i++ { if i%2 == 0 { ans[i] = l l++ } else { ans[i] = r r-- } } for i := k; i < n; i++ { if k%2 == 0 { ans[i] = r r-- } else { ans[i] = l l++ } } return ans }(code-box)

function constructArray(n: number, k: number): number[] { let l = 1; let r = n; const ans = new Array(n); for (let i = 0; i < k; ++i) { ans[i] = i % 2 == 0 ? l++ : r--; } for (let i = k; i < n; ++i) { ans[i] = k % 2 == 0 ? r-- : l++; } return ans; }(code-box)