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  • 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:

    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]

    Approach #1: DP. [C++]

    class Solution {
    public:
        vector<int> largestDivisibleSubset(vector<int>& nums) {
            int size = nums.size();
            
            sort(nums.begin(), nums.end());
            
            vector<int> dp(size, 1);
            vector<int> tmp(size, -1);
            vector<int> ans;
            
            if (size == 0) return ans;
            
            int idx = 0;
            for (int i = 0; i < size; ++i) {
                for (int j = 0; j < i; ++j) {
                    if (nums[i] % nums[j] == 0 && dp[i] < dp[j] + 1) {
                        dp[i] = dp[j] + 1;
                        tmp[i] = j;
                    }
                    if (dp[i] > dp[idx]) idx = i;
                }
            }
            for (int i = idx; i != -1; i = tmp[i]) 
                ans.push_back(nums[i]);
            //reverse(ans.begin(), ans.end());
            
            return ans;
        }
    };
    

      

    Analysis:

    dp[i] : represent the number of elements in the subset which index from 0 to i.

    tmp[i]: the previous factor's index of nums[i].

    永远渴望,大智若愚(stay hungry, stay foolish)
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  • 原文地址:https://www.cnblogs.com/h-hkai/p/10389723.html
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