526. Beautiful Arrangement
作者:互联网
package LeetCode_526 /** * 526. Beautiful Arrangement * https://leetcode.com/problems/beautiful-arrangement/ * Suppose you have n integers labeled 1 through n. * A permutation of those n integers perm (1-indexed) is considered a beautiful arrangement if for every i (1 <= i <= n), either of the following is true: perm[i] is divisible by i. i is divisible by perm[i]. Given an integer n, return the number of the beautiful arrangements that you can construct. Example 1: Input: n = 2 Output: 2 Explanation: The first beautiful arrangement is [1,2]: - perm[1] = 1 is divisible by i = 1 - perm[2] = 2 is divisible by i = 2 The second beautiful arrangement is [2,1]: - perm[1] = 2 is divisible by i = 1 - i = 2 is divisible by perm[2] = 1 Example 2: Input: n = 1 Output: 1 Constraints: 1. 1 <= n <= 15 * */ class Solution { /* * Solution: DFS, to check the numbers of 1-n if can match beautiful arrangement, * Time:O(2^n), Space:O(2^n) * */ private var result = 0 fun countArrangement(n: Int): Int { val used = BooleanArray(n+1) dfs(n,n,used) return result } private fun dfs(N: Int, n: Int, used: BooleanArray) { if (n == 0) { result++ return } for (i in 1..N) { if (used[i] || i % n != 0 && n % i != 0) { continue } used[i] = true dfs(N, n - 1, used) used[i] = false } } }
标签:Beautiful,beautiful,integers,arrangement,526,Arrangement 来源: https://www.cnblogs.com/johnnyzhao/p/15202024.html