Day11-q1 sol added #318

Author: Tech-neophyte

Day-11/Find Eventual Safe States/Tech-neophyte--c.md

@@ -0,0 +1,43 @@
+# Approach
+<br/>Remove the nodes having outdegree 0 and add to ans , if no nodes return.
+<br/>The nodes which are connected to the above nodes will have 1 less outdegree. Repeat for all O outdegree nodes.
+<br/>Sort the ans and return.
+```
+class Solution {
+public:
+    vector<int> eventualSafeNodes(vector<vector<int>>& graph) {
+        int n=graph.size();
+        vector<int> outdegree(n,0);
+        unordered_map<int,vector<int>> m;
+        for(int i=0;i<n;i++)
+        {
+            for(auto it : graph[i])
+            {
+                m[it].push_back(i);
+            }
+            outdegree[i]=graph[i].size();
+        }
+        vector<int> ans;
+        vector<int> visited(n,0);
+        while(true)
+        {
+            bool flag=0;
+            for(int i=0;i<n;i++)
+            {
+                if(!visited[i] && outdegree[i]==0)
+                {
+                    ans.push_back(i);
+                    visited[i]=1;
+                    flag=1;
+                    for(auto it : m[i])
+                    outdegree[it]--;
+                }
+            }
+            if(!flag)
+            break;
+        }
+        sort(ans.begin(),ans.end());
+        return ans;
+    }
+};
+```