Create AlienDictionary.cpp

Graphs/AlienDictionary.cpp

@@ -0,0 +1,55 @@
+class Solution{
+    private:
+    vector<int>topoSort(int V,vector<int>adj[]){
+        int indegree[V]={0};
+        for(int i=0;i<V;i++){
+            for(auto it:adj[i]){
+                indegree[it]++;
+            }
+        }
+        queue<int>q;
+        for(int i=0;i<V;i++){
+            if(indegree[i]==0){
+                q.push(i);
+            }
+
+        }vector<int>topo;
+        while(!q.empty()){
+            int node=q.front();
+            q.pop();
+            topo.push_back(node);
+
+            for(auto it:adj[node]){
+                indegree[it]--;
+                if(indegree[it]==0){
+                    q.push(it);
+                }
+            }
+        }
+        return topo;
+    }
+    public:
+    string findOrder(string dict[], int N, int K) {
+        //code here
+        vector<int>adj[K];
+        for(int i=0;i<N-1;i++){
+            string s1=dict[i];
+            string s2=dict[i+1];
+            int len=min(s1.size(),s2.size());
+            for(int ptr=0;ptr<len;ptr++){
+                if(s1[ptr]!=s2[ptr]){
+                    adj[s1[ptr]-'a'].push_back(s2[ptr]-'a');
+                    break;
+                }
+
+            }
+        }
+        vector<int>topo=topoSort(K,adj);
+
+    string ans="";
+    for(auto it:topo){
+        ans=ans+char(it+'a');
+    }
+    return ans;
+    }
+};