Course Schedule

from collections import deque

def find_course_order(n, m, prerequisites):
    adj = [[] for _ in range(n + 1)]
    in_degree = [0] * (n + 1)
    
    for a, b in prerequisites:
        adj[a].append(b)
        in_degree[b] += 1
   
    queue = deque()
    for i in range(1, n + 1):
        if in_degree[i] == 0:
            queue.append(i)
   
    topo_order = []
    while queue:
        course = queue.popleft()
        topo_order.append(course)
      
        for neighbor in adj[course]:
            in_degree[neighbor] -= 1
            if in_degree[neighbor] == 0:
                queue.append(neighbor)
    
    if len(topo_order) == n:
        return topo_order
    else:
        return "IMPOSSIBLE"

n, m = map(int, input().split())
prerequisites = [tuple(map(int, input().split())) for _ in range(m)]

result = find_course_order(n, m, prerequisites)
if result == "IMPOSSIBLE":
    print(result)
else:
    print(' '.join(map(str, result)))

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