lexicographical topological sorting - Airbnb

Author: offamitkumar

Diff for: Solution/Day-092.cpp

@@ -0,0 +1,53 @@
+#include <bits/stdc++.h>
+using namespace std;
+class Solution{
+    private:
+        set<string>id; 
+        map<string , int>in_deg;
+        map<string , set<string>>graph;
+        vector<string> Sort(void){
+            vector<string>res;
+            while(!id.empty()){
+                string current = *(id.begin());
+                id.erase(current);
+                res.push_back(current);
+                for(auto&itr:graph[current]){
+                    in_deg[itr]--;
+                    if(in_deg[itr]==0){
+                        id.insert(itr);
+                    }
+                }
+            }
+            return res;
+        }
+    public:
+        vector<string> topologicalSort(map<string , vector<string>>&cID){
+            // C++ map maintain sorted already so we don't have to sort the courses
+            // If it wasn't map then we have to first sort the course , then their pre-requisites
+            for(auto&courses:cID){
+                if(courses.second.size() == 0){
+                    id.insert(courses.first);
+                }else{
+                    for(auto&itr:courses.second){
+                        graph[itr].insert(courses.first);
+                    }
+                }
+                in_deg[courses.first] = courses.second.size();
+            }
+            return Sort();
+        }
+};
+int main(void){
+    map<string , vector<string>> cID{
+            {"CSC300" , {"CSC100" , "CSC200"}},
+            {"CSC200" , {"CSC100"}},
+            {"CSC100" , {}}
+    }; 
+    Solution s1;
+    vector<string>v = s1.topologicalSort(cID);
+    for(auto&itr:v){
+        cout << itr << ' ';
+    }
+    cout << '\n'; 
+    return 0;
+}