Leetcode: 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]

解法：

动态规划

class Solution {
public:
vector<int> largestDivisibleSubset(vector<int>& nums) {
vector<int> result;
vector<int> table(nums.size(), 1);
vector<int> pre(nums.size(), -1);

if (nums.empty()) return result;

sort(nums.begin(), nums.end());

for (int i = 1; i < table.size(); ++i) {
for (int j = i-1; j >= 0; --j) {
if ((nums[i] % nums[j]) == 0) {
if (table[j] + 1 > table[i]) {
table[i] = table[j] + 1;
pre[i] = j;
}
}
}
}

int max = 0;
int idx = 0;
for (int i = 0; i < table.size(); ++i) {
if (table[i] > max) {
idx = i;
max = table[i];
}
}

do {
result.push_back(nums[idx]);
idx = pre[idx];
} while(idx >= 0);

return result;
}
};