[Swift]LeetCode368. 最大整除子集 | Largest Divisible Subset

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Given a set of distinct positive integers, find the largest subset such that every pair (Si, Sj) of elements in this subset satisfies:

Si % Sj = 0 or Sj % Si = 0.

If there are multiple solutions, return any subset is fine.

Example 1:

Input: [1,2,3]
Output: [1,2] (of course, [1,3] will also be ok) 

Example 2:

Input: [1,2,4,8]
Output: [1,2,4,8]

---

给出一个由无重复的正整数组成的集合，找出其中最大的整除子集，子集中任意一对 (Si，Sj) 都要知足：Si % Sj = 0 或 Sj % Si = 0。

若是有多个目标子集，返回其中任何一个都可。 

示例 1:

输入: [1,2,3]
输出: [1,2] (固然, [1,3] 也正确)

示例 2:

输入: [1,2,4,8]
输出: [1,2,4,8]

---

476ms

 1 class Solution {
 2     func largestDivisibleSubset(_ nums: [Int]) -> [Int] {
 3         var nums = nums.sorted(by:<)
 4         var res:[Int] = [Int]()
 5         let number:Int = nums.count
 6         var dp:[[Int]] = [[Int]](repeating:[Int](repeating:0,count:2),count:number)
 7         var mx:Int = 0
 8         var mx_idx:Int = 0
 9         for i in 0..<number
10         {
11             for j in stride(from:i,through:0,by:-1)
12             {
13                 if nums[i] % nums[j] == 0 && dp[i][0] < dp[j][0] + 1
14                 {
15                     dp[i][0] = dp[j][0] + 1
16                     dp[i][1] = j
17                     if mx < dp[i][0]
18                     {
19                         mx = dp[i][0]
20                         mx_idx = i
21                     }                    
22                 }
23             }
24         }
25         for i in 0..<mx
26         {
27             res.append(nums[mx_idx])
28             mx_idx = dp[mx_idx][1]            
29         }
30         return res
31     }
32 }