Leetcode 368. Largest Divisible Subset

Posted 2020-07-31 Deribs4

368. Largest Divisible Subset

Total Accepted: 864 Total Submissions: 2728 Difficulty: Medium

 

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:

nums: [1,2,3]

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

 

Example 2:

nums: [1,2,4,8]

Result: [1,2,4,8]

 

思路：

定义T[n]为最大值为nums[n]的满足题意的子集元素个数。
显然如果存在i（i<n），有nums[n]%nums[i]，T[n]=max{T[i]+1}；否则，T[n]=1。

 

代码：

 1 class Solution {
 2 public:
 3     vector<int> largestDivisibleSubset(vector<int>& nums) {
 4         int i,j,len=nums.size(),m=0,mi;
 5         vector<int> T(len,0);
 6         vector<int> son(len,0);
 7         sort(nums.begin(),nums.end());
 8         for(i=0;i<len;i++){
 9             for(j=i;j>=0;j--){
10                 if(nums[i]%nums[j]==0&&T[j]+1>T[i]){
11                     T[i]=T[j]+1;
12                     son[i]=j;
13                 }
14             }
15             if(T[i]>m){
16                 m=T[i];
17                 mi=i;
18             }
19         }
20         vector<int> re;
21         for(i=0;i<m;i++){
22             re.insert(re.begin(),nums[mi]);
23             mi=son[mi];
24         }
25         return re;
26     }
27 };