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authorjack <0x6A73@pm.me>2024-06-14 13:13:15 -0600
committerjack <0x6A73@pm.me>2024-06-14 13:13:15 -0600
commitd343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa (patch)
tree96df922dae2a5073d9a50ea70c7aae6aa37e3ebe /sort_items_dependencies.cpp
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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(int) & 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(int) 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");
+}