LeetCode:Largest Divisible Subset

368. Largest Divisible Subset

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：比较有趣的一个题目，首先排序后参考最长递增子序列就可以了。

bool isdiv(vector<int>&arr, int now)
{
    for (int i = 0; i < arr.size(); i++)
        if (now%arr[i] != 0)
            return false;
    return true;
}
vector<int> largestDivisibleSubset(vector<int>& nums)
{
    vector<vector<int>>r;
    vector<int>pos,e;
    sort(nums.begin(), nums.end());
    int size = nums.size();
    if (size == 0)
        return e;
    e.push_back(nums[0]);
    r.push_back(e);
    for (int i = 1; i < size; i++)
    {
        int maxv = -1;
        vector<int>t;
        for (int j = 0; j < i; j++)
        {
            if (isdiv(r[j], nums[i]) && (int)r[j].size() > maxv)
            {
                maxv = r[j].size();
                t.clear();
                t = r[j];
            }
        }
        t.push_back(nums[i]);
        r.push_back(t);
    }
    int maxi = 0;
    int maxv = -1;
    for (int i = 0; i < r.size(); i++)
    {
        if ((int)r[i].size()>maxv)
        {
            maxv = r[i].size();
            maxi = i;
        }
    }
    return r[maxi];
}

 

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