Alien Dictionary GFG

class Solution{
    //algo for topological sort 
    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) {
        //created adj
        vector<int> adj[K];
        //started a loop to traverse all given string
        for(int i=0;i<N-1;i++){
            string s1 = dict[i];
            string s2 = dict[i+1];
            //get the min size of string 
            int len = min(s1.size(), s2.size());
            //now comapare and push them into the adj
            for(int j=0;j<len;j++){
                if(s1[j] != s2[j]){
                    adj[s1[j] - 'a'].push_back(s2[j] - 'a');
                    break;
                }
            }
        }
        // call for topo sort function
        vector<int> topo = topoSort(K, adj);
        //expected a string to be return 
        string ans= "";
        for(auto it: topo){
            ans = ans + char(it + 'a');
        }
        return ans;
    }
};