Course Schedule

import sys
import heapq
from collections import deque

input = sys.stdin.readline
INF = float("inf")

def I():  return int(input())
def MI(): return map(int, input().split())
def LI(): return list(map(int, input().split()))
def S():  return input().strip()

def topo_sort(n, adj):
    indeg = [0] * (n + 1)
    for u in range(1, n + 1):
        for v in adj[u]:
            indeg[v] += 1

    q = deque(u for u in range(1, n + 1) if indeg[u] == 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)

    return order if len(order) == n else None

def read_graph(n, m, directed=True):
    adj = [[] for _ in range(n + 1)]
    for _ in range(m):
        a, b, *w = MI()
        adj[a].append((b, w[0]) if w else b)
        if not directed:
            adj[b].append((a, w[0]) if w else a)
    return adj

n, m = MI()
adj = read_graph(n, m)

order = topo_sort(n, adj)
print("IMPOSSIBLE" if order is None else " ".join(map(str, order)))

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED