Submission #588509

#	Time	Username	Problem	Language	Result	Execution time	Memory
588509		Vandflaske	Love Polygon (BOI18_polygon)	Cpython 3	0 / 100	2065 ms	19772 KiB

polygon

import sys
n = int(sys.stdin.readline())
personer = []
elsket1 = []
elsket2 = []
A = []
pile = 0

for _ in range(n):
    s, t = map(str, sys.stdin.readline().split())
    personer.append(s)
    elsket1.append(t)

for l in range(n):
    elsket2.append(personer.index(elsket1[l]))

for _ in range(n):
    A.append(0)

for i in range(n):
    if n % 2 == 1:
        break
    if A[i] == 0 and A[elsket2[i]] == 0 and i == elsket2[elsket2[i]] and i != elsket2[i]:
        A[elsket2[i]] = 1
        A[i] = 1

for j in range(n):
    if n % 2 == 1:
        break
    if A[j] == 0 and A[elsket2[j]] == 0 and j != elsket2[j]:
        A[j] = 1
        A[elsket2[j]] = 1
        pile += 1

if n % 2 == 1:
    print(-1)
else:
    print(pile + A.count(0))

• Subtask 1: 0 / 21
• Subtask 2: 0 / 25
• Subtask 3: 0 / 29
• Subtask 4: 0 / 25