[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) 都要满足：Si % Sj = 0 或 Sj % Si = 0。

如果有多个目标子集，返回其中任何一个均可。 

示例 1:

输入: [1,2,3]
输出: [1,2] (当然, [1,3] 也正确)

示例 2:

输入: [1,2,4,8]
输出: [1,2,4,8]

---

476ms

class Solution {
    func largestDivisibleSubset(_ nums: [Int]) -> [Int] {
        var nums = nums.sorted(by:<)
        var res:[Int] = [Int]()
        let number:Int = nums.count
        var dp:[[Int]] = [[Int]](repeating:[Int](repeating:0,count:2),count:number)
        var mx:Int = 0
        var mx_idx:Int = 0
        for i in 0..<number
        {
            for j in stride(from:i,through:0,by:-1)
            {
                if nums[i] % nums[j] == 0 && dp[i][0] < dp[j][0] + 1
                {
                    dp[i][0] = dp[j][0] + 1
                    dp[i][1] = j
                    if mx < dp[i][0]
                    {
                        mx = dp[i][0]
                        mx_idx = i
                    }                    
                }
            }
        }
        for i in 0..<mx
        {
            res.append(nums[mx_idx])
            mx_idx = dp[mx_idx][1]            
        }
        return res
    }
}