what is topological sorting code example

Example 1: topological sorting

int n; // number of vertices
vector<vector<int>> adj; // adjacency list of graph
vector<bool> visited;
vector<int> ans;

void dfs(int v) {
    visited[v] = true;
    for (int u : adj[v]) {
        if (!visited[u])
            dfs(u);
    }
    ans.push_back(v);
}

void topological_sort() {
    visited.assign(n, false);
    ans.clear();
    for (int i = 0; i < n; ++i) {
        if (!visited[i])
            dfs(i);
    }
    reverse(ans.begin(), ans.end());
}

Example 2: topological sort

def topological_sort():
    for each node:
        if visited[node] is False:
            dfs(node)
def dfs(node):
    visited[node] = True
    for nei in neighbours[node]:
        dfs(node)
    ret.insert_at_the _front(node)