Create remove-methods-from-project.cpp

Author: kamyu104

C++/remove-methods-from-project.cpp

@@ -0,0 +1,48 @@
+// Time:  O(n + e)
+// Space: O(n + e)
+
+// bfs
+class Solution {
+public:
+    vector<int> remainingMethods(int n, int k, vector<vector<int>>& invocations) {
+        vector<vector<int>> adj(n);
+        const auto& bfs = [&]() {
+            vector<bool> lookup(n);
+            lookup[k] = true;
+            vector<int> q = {k};
+            while (!empty(q)) {
+                vector<int> new_q;
+                for (const auto& u : q) {
+                    for (const auto& v : adj[u]) {
+                        if (lookup[v]) {
+                            continue;
+                        }
+                        lookup[v] = true;
+                        new_q.emplace_back(v);
+                    }
+                }
+                q = move(new_q);
+            }
+            return lookup;
+        };
+       
+        for (const auto& e : invocations) {
+            adj[e[0]].emplace_back(e[1]);
+        }
+        const auto& lookup = bfs();
+        for (const auto& e : invocations) {
+            if (lookup[e[0]] != lookup[e[1]]) {
+                vector<int> result(n);
+                iota(begin(result), end(result), 0);
+                return result;
+            }
+        }
+        vector<int> result;
+        for (int u = 0; u < n; ++u) {
+            if (!lookup[u]) {
+                result.emplace_back(u);
+            }
+        }
+        return result;
+    }
+};