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// 1203. Sort Items by Groups Respecting Dependencies
#include "leetcode.h"
/*
* there are 'n' items in each belonging to zero or one of 'm' groups where
* 'group[i]' is the group that the i'th item beglons to and it's equal to '-1'
* if the i'th item beglongs to no group. the items and the groups are zero
* indexed. a group can have no item belonging to it. return a sorted list of
* the items such that
* - the items that belong to the same group are next to each other in the
* sorted list
* - there are some relations between these items where 'beforeItems[i]' is a
* list containing all the items that should come before the i'th item in the
* sorted array (to the left of the i'th item) return any solution if there is
* more than one solution and return an empty list if there is no solution.
*/
class Solution {
bool top_sort(vector<unordered_set<int>> &al, int i, vector<int> &res,
vector<int> &stat) {
if (stat[i])
return stat[i] == 2;
stat[i] = 1;
for (auto n : al[i])
if (!top_sort(al, n, res, stat))
return false;
stat[i] = 2;
res.push_back(i);
return true;
}
public:
vector<int> sortItems(int n, int m, vector<int> &group,
vvd & beforeItems) {
vector<int> ans(n), stat(n + 2 * m), ans_tmp;
vector<unordered_set<int>> al(n + 2 * m);
for (auto i = 0; i < n; ++i) {
if (group[i] != -1) {
al[n + group[i]].insert(i);
al[i].insert(n + m + group[i]);
}
for (auto j : beforeItems[i]) {
if (group[i] != -1 && group[i] == group[j])
al[j].insert(i);
else {
auto ig = group[i] == -1 ? i : n + group[i];
auto jg = group[j] == -1 ? j : n + m + group[j];
al[jg].insert(ig);
}
}
}
for (int n = al.size() - 1; n >= 0; --n)
if (!top_sort(al, n, ans_tmp, stat))
return {};
reverse(begin(ans_tmp), end(ans_tmp));
copy_if(begin(ans_tmp), end(ans_tmp), ans.begin(),
[&](int i) { return i < n; });
return ans;
}
};
int main() {
Solution obj;
vector<int> g1 = {-1, -1, 1, 0, 0, 1, 0, -1},
g2 = {-1, -1, 1, 0, 0, 1, 0, -1};
vvd bi1 = {{}, {6}, {5}, {6}, {3, 6}, {}, {}, {}},
bi2 = {{}, {6}, {5}, {6}, {3}, {}, {4}, {}};
for (auto i : obj.sortItems(8, 2, g1, bi1))
printf("%d ", i); // expect: [6,3,4,1,5,2,0,7]
printf("\n");
for (auto i : obj.sortItems(8, 2, g2, bi2))
printf("%d ", i); // expect: []
printf("\n");
}
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