#### Topological Sort by Kahns Algo

P
```#include <cstdio>
#include <cstring>
#include <iostream>
#include <queue>
#include <vector>

std::vector<int> topoSortKahn(int N, const std::vector<std::vector<int> > &adj);

int main() {
int nodes = 0, edges = 0;
std::cin >> edges >> nodes;
if (edges == 0 || nodes == 0) {
return 0;
}
int u = 0, v = 0;

std::vector<std::vector<int> > graph(nodes);
// create graph
// example
// 6 6
// 5 0 5 2 2 3 4 0 4 1 1 3

for (int i = 0; i < edges; i++) {
std::cin >> u >> v;
graph[u].push_back(v);
}

std::vector<int> topo = topoSortKahn(nodes, graph);
// topologically sorted nodes
for (int i = 0; i < nodes; i++) {
std::cout << topo[i] << " ";
}
}

std::vector<int> topoSortKahn(int V,
std::vector<bool> vis(V + 1, false);
std::vector<int> deg(V + 1, 0);
for (int i = 0; i < V; i++) {
for (int j : adj[i]) {
deg[j]++;
}
}
std::queue<int> q;
for (int i = 0; i < V; i++) {
if (deg[i] == 0) {
q.push(i);
vis[i] = true;
}
}
std::vector<int> arr(V + 1, 0);
int count = 0;
while (!q.empty()) {
int cur = q.front();
q.pop();
arr[count++] = cur;
for (int i : adj[cur]) {
if (!vis[i]) {
deg[i]--;
if (deg[i] == 0) {
q.push(i);
vis[i] = true;
}
}
}
}
return arr;
}
```