1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
| class Solution {
public:
vector<int> sortItems(int n, int m, vector<int>& group, vector<vector<int>>& beforeItems) {
vector<vector<int>> groupItem(n + m);
int leftId = m;
for (int i = 0; i < n; ++i) {
if (group[i] == -1)
group[i] = leftId++;
groupItem[group[i]].emplace_back(i);
}
vector<vector<int>> groupGraph(n + m);
vector<vector<int>> itemGraph(n);
vector<int> groupDegree(n + m, 0);
vector<int> itemDegree(n, 0);
for (int i = 0; i < n; ++i) {
int curGroupId = group[i];
for (auto& item: beforeItems[i]) {
int beforeGroupId = group[item];
if (beforeGroupId == curGroupId) {
++itemDegree[i];
itemGraph[item].emplace_back(i);
} else {
++groupDegree[curGroupId];
groupGraph[beforeGroupId].emplace_back(curGroupId);
}
}
}
vector<int> id;
for (int i = 0; i < n + m; ++i)
id.emplace_back(i);
vector<int> groupTopSort = topSort(groupDegree, groupGraph, id);
if (groupTopSort.size() == 0)
return vector<int>{};
vector<int> ans;
for (auto& curGroupId: groupTopSort) {
int size = groupItem[curGroupId].size();
if (size == 0) continue;
vector<int> itemTopSort = topSort(itemDegree, itemGraph, groupItem[curGroupId]);
if (itemTopSort.size() == 0) return vector<int>{};
ans.insert(ans.end(), itemTopSort.begin(), itemTopSort.end());
}
return ans;
}
private:
vector<int> topSort(vector<int>& indeg, vector<vector<int>>& graph, vector<int>& items) {
queue<int> q;
for (auto& item: items)
if (indeg[item] == 0)
q.push(item);
vector<int> ans;
while (!q.empty()) {
int u = q.front(); q.pop();
ans.emplace_back(u);
for (auto& v: graph[u])
if (--indeg[v] == 0)
q.push(v);
}
return ans.size() == items.size() ? ans : vector<int>{};
}
};
|