topological sort cp algorithms

1int n; // number of vertices
2vector<vector<int>> adj; // adjacency list of graph
3vector<bool> visited;
4vector<int> ans;
5
6void dfs(int v) {
7    visited[v] = true;
8    for (int u : adj[v]) {
9        if (!visited[u])
10            dfs(u);
11    }
12    ans.push_back(v);
13}
14
15void topological_sort() {
16    visited.assign(n, false);
17    ans.clear();
18    for (int i = 0; i < n; ++i) {
19        if (!visited[i])
20            dfs(i);
21    }
22    reverse(ans.begin(), ans.end());
23}
24

1//Topological sort DFS
2//Complete code 
3//Possible Only on DAG(Directed Acyclic Graph)
4#include<bits/stdc++.h>
5using namespace std;
6void addedge(vector<int>adj[],int u,int v)
7{
8    adj[u].push_back(v);
9
10}
11void topo(int val,stack<int>&st,vector<int>adj[],vector<int>&visited)
12{
13    visited[val]=1;
14    for(auto i:adj[val])
15    {
16        if(!visited[i])
17        {
18            topo(i,st,adj,visited);
19        }
20    }
21    st.push(val);
22}
23void toposort(vector<int>adj[],int n)
24{
25    stack<int>st;
26    vector<int>visited(n,0);
27    for(int i=0;i<n;i++)
28    {
29        if(visited[i]==0)
30        {
31            topo(i,st,adj,visited);
32        }
33    }
34    vector<int>topo;
35    while(!st.empty())
36    {
37        topo.push_back(st.top());
38        st.pop();
39    }
40    int s=topo.size();
41    for(int j=0;j<s;j++)
42    {
43        cout<<topo[j]<<" ";
44    }
45}
46int main()
47{
48    int vertex,edges;
49    cout<<"Enter the vertex and edges"<<endl;
50    cin>>vertex>>edges;
51    vector<int>adj[vertex];
52    int a,b;
53    cout<<"Enter the links"<<endl;
54    for(int i=0;i<vertex;i++)
55    {
56        cin>>a>>b;
57        addedge(adj,a,b);
58    }
59    toposort(adj,vertex);
60    return 0;
61}
62