提出 #7269913

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ソースコード 拡げる

import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 7)

from collections import deque

N = int(input())
A = [[-1] + [int(x)-1 for x in row.split()][::-1] for row in sys.stdin.readlines()]

A.append([-1])

def f():
    can_use = [n for n in range(N) if A[A[n][-1]][-1] == n]
    for n in can_use:
        A[n].pop()
    return len(can_use)

answer = 0
rest = N*(N-1)
while True:
    answer += 1
    x = f()
    if x == 0:
        answer = -1
        break
    rest -= x
    if rest == 0:
        break

print(answer)

提出情報

ジャッジ結果