Create 1466-reorder-routes-to-make-all-paths-lead-to-the-city-zero.cpp

Author: Ritesh7766

Diff for: cpp/1466-reorder-routes-to-make-all-paths-lead-to-the-city-zero.cpp

@@ -0,0 +1,36 @@
+class Solution {
+public:
+    int minReorder(int n, vector<vector<int>>& connections) {
+        unordered_map<int, vector<pair<int, bool>>> graph;
+        unordered_set<int> visited;
+
+        for (int i = 0; i < n; i++)
+            graph[i] = vector<pair<int, bool>>{};
+
+        for (vector<int> connection : connections) {
+            graph[connection[0]].push_back(make_pair(connection[1], true));
+            graph[connection[1]].push_back(make_pair(connection[0], false));
+        }
+
+        int cnt = 0;
+        stack<int> stk;
+        stk.push(0);
+        visited.insert(0);
+
+        while (!stk.empty()) {
+            int u = stk.top();
+            stk.pop();
+            for (pair<int, bool> v : graph[u]) {
+                if (visited.count(v.first))
+                    continue;
+                stk.push(v.first);
+                visited.insert(v.first);
+                if (v.second)
+                    cnt += 1;
+            }
+        }
+
+        return cnt;
+    }
+};
+