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

@@ -0,0 +1,32 @@
+class Solution {
+public:
+    int minReorder(int n, vector<vector<int>>& con) {
+        vector<vector<int>> adj(n) , bk(n);
+        vector<int> vis(n,0);
+        vis[0] =1;
+        for(auto a : con){
+            adj[a[0]].push_back(a[1]);
+            bk[a[1]].push_back(a[0]);
+        }
+        int ans=0;
+        queue<int> q;
+        q.push(0);
+        while(!q.empty()){
+            int a = q.front();
+            vis[a] =1;
+            q.pop();
+            for( int no : adj[a]){
+                if(!vis[no]){
+                    ans++;
+                    q.push(no);
+                }
+            }
+            for( int no : bk[a]){
+                if(!vis[no]){
+                    q.push(no);
+                }
+            }
+        }
+        return ans;
+    }
+};