Distinct Routes

import sys
from collections import deque, defaultdict, Counter
from heapq import heappush, heappop, heapify
from bisect import bisect_left, bisect_right
from itertools import permutations, combinations, product, accumulate, groupby
from functools import lru_cache, cmp_to_key, reduce
from math import gcd, isqrt, comb, inf, pi, sqrt, atan2, hypot


def main():
    data = sys.stdin.buffer.read().split(); idx = 0
    # n = int(data[idx]); idx += 1
    n, m = map(int, data[idx:idx + 2]); idx += 2
    # a = list(map(int, data[idx:idx + n])); idx += n
    # s = data[idx].decode(); idx += 1                  # strings

    adj = [[] for i in range(n+1)]
    for i in range(m):
        a, b = map(int, data[idx:idx + 2]); idx += 2
        adj[a].append((b,i))


    # working_paths_node =  [[] for i in range(n+1)]
    out = []

    used = set()

    taken_path = []


    bestdays = [0]
    best_out = []


    def dfs(node, bestdays, best_out):
        taken_path.append(node)
        # print(f"{node=}. {taken_path=}")
        if node == n:
            # out.append(taken_path.copy())
            # taken_path.pop()
            taken_path.append(-1)
            days = taken_path.count(-1)
            # print(f"{days=}")
            if days > bestdays[0]:
                bestdays[0] = days
                best_out = taken_path.copy()
                # print(f"{best_out=}")

            best_out = dfs(1, bestdays, best_out)
            taken_path.pop()
            taken_path.pop()
            return best_out

        neighbours = adj[node]
        for newnode, path in neighbours:
            if path in used: continue
            used.add(path)
            best_out = dfs(newnode, bestdays, best_out)
            used.remove(path)

        taken_path.pop()
        return best_out

    best_out = dfs(1, bestdays, best_out)
    # print(best_out)



    # g = [data[idx + i].decode() for i in range(n)]; idx += n  # grid of n rows, no spaces, strings

    # input = sys.stdin.readline
    # n, m = map(int, input().split())
    # s = input().strip()  # strip removes the trailing newline
    # for line in sys.stdin:  # read until EOF



    days= best_out.count(-1)

    print(days)
    # for paths in out:
    #     print(len(paths))
    #     print(" ".join(map(str, paths)))

    day = []
    for i in range(len(best_out)):
        if best_out[i] == -1:
            print(len(day))
            print(" ".join(map(str, day)))  
            day = []
        else:
            day.append(best_out[i])
    # sys.stdout.write("\n".join(map(str, out)) + "\n")  # one value per line
    # print(*out)                                      # space separated on one line
    # print(f"{ans:.6f}")                              # float with 6 decimals
    # print("\n".join("".join(row) for row in g))      # grid of chars


main()

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: TIME LIMIT EXCEEDED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: TIME LIMIT EXCEEDED

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: TIME LIMIT EXCEEDED