Graph Exploration Target: 15s
BFS-based topo sort processes zero-indegree nodes first. Detects cycles if order is incomplete.
from collections import deque
q = deque(n for n in range(V) if indeg[n] == 0)
order = []
while q:
u = q.popleft()
order.append(u)
for v in adj[u]:
indeg[v] -= 1
if indeg[v] == 0: q.append(v)Type it from memory. Go.