結果
| 問題 |
No.3321 岩井星人グラフ-1
|
| コンテスト | |
| ユーザー |
 lif4635
|
| 提出日時 | 2025-10-31 23:04:25 |
| 言語 | PyPy3 (7.3.15) |
| 結果 |
WA
|
| 実行時間 | - |
| コード長 | 6,872 bytes |
| コンパイル時間 | 308 ms |
| コンパイル使用メモリ | 82,904 KB |
| 実行使用メモリ | 144,924 KB |
| 最終ジャッジ日時 | 2025-10-31 23:04:48 |
| 合計ジャッジ時間 | 20,639 ms |
|
ジャッジサーバーID （参考情報） |
judge3 / judge2 |
（要ログイン）
| ファイルパターン | 結果 |
|---|---|
| sample | AC * 2 WA * 1 |
| other | AC * 52 WA * 35 RE * 2 |
ソースコード
# input
import sys
input = sys.stdin.readline
II = lambda : int(input())
MI = lambda : map(int, input().split())
LI = lambda : [int(a) for a in input().split()]
SI = lambda : input().rstrip()
LLI = lambda n : [[int(a) for a in input().split()] for _ in range(n)]
LSI = lambda n : [input().rstrip() for _ in range(n)]
MI_1 = lambda : map(lambda x:int(x)-1, input().split())
LI_1 = lambda : [int(a)-1 for a in input().split()]
mod = 998244353
inf = 1001001001001001001
ordalp = lambda s : ord(s)-65 if s.isupper() else ord(s)-97
ordallalp = lambda s : ord(s)-39 if s.isupper() else ord(s)-97
yes = lambda : print("Yes")
no = lambda : print("No")
yn = lambda flag : print("Yes" if flag else "No")
prinf = lambda ans : print(ans if ans < 1000001001001001001 else -1)
alplow = "abcdefghijklmnopqrstuvwxyz"
alpup = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
alpall = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
URDL = {'U':(-1,0), 'R':(0,1), 'D':(1,0), 'L':(0,-1)}
DIR_4 = [[-1,0],[0,1],[1,0],[0,-1]]
DIR_8 = [[-1,0],[-1,1],[0,1],[1,1],[1,0],[1,-1],[0,-1],[-1,-1]]
DIR_BISHOP = [[-1,1],[1,1],[1,-1],[-1,-1]]
prime60 = [2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59]
sys.set_int_max_str_digits(0)
# sys.setrecursionlimit(10**6)
# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
from collections import defaultdict,deque
from heapq import heappop,heappush
from bisect import bisect_left,bisect_right
DD = defaultdict
BSL = bisect_left
BSR = bisect_right
class DSU:
n : int
par : list[int]
siz : list[int]
fix_leader : bool
__slots__ = ["n", "par", "siz", "fix_leader"]
def __init__(self, n, fix_leader = False):
self.n = n
self.par = [*range(n)]
self.siz = [1] * n
self.fix_leader = fix_leader
def leader(self, a):
while self.par[a] != a:
a = self.par[self.par[a]]
self.par[a] = self.par[self.par[a]]
return a
def merge(self, a, b):
a = self.leader(a)
b = self.leader(b)
if a == b: return a
if self.fix_leader or self.siz[a] > self.siz[b]:
self.siz[a] += self.siz[b]
self.par[b] = a
return a
else:
self.siz[b] += self.siz[a]
self.par[a] = b
return b
def same(self, a, b):
return self.leader(a) == self.leader(b)
def size(self, a):
return self.siz[self.leader(a)]
def groups(self):
res = [[] for i in range(self.n)]
for i in range(self.n):
res[self.leader(i)].append(i)
res2 = []
for i in range(self.n):
if len(res[i]) > 0:
res2.append(res[i])
return res2
n, m = MI()
if n - 1 != m:
no()
exit()
uf = DSU(n)
d = [0] * n
e = [[] for i in range(n)]
for i in range(n - 1):
a, b = MI_1()
uf.merge(a, b)
d[a] += 1
d[b] += 1
e[a].append(b)
e[b].append(a)
g = uf.groups()
if len(g) >= 3:
no()
exit()
dc = [0] * 4
for i in range(n):
if d[i] >= 4:
no()
exit()
dc[d[i]] += 1
def check(e):
d = [len(e[i]) for i in range(n)]
for i in range(n):
if d[i] >= 4:
return False
dis = [-1] * n
st = []
for u in range(n):
if d[u] == 3:
cnt = 0
dis[u] = 0
for v in e[u]:
if d[v] == 3:
cnt += 1
else:
st.append(v)
dis[v] = 1
if cnt != 2:
return False
leaf = []
while st:
u = st.pop()
if len(e[u]) == 1:
leaf.append(dis[u])
continue
f = 0
for v in e[u]:
if dis[v] == -1:
f += 1
dis[v] = dis[u] + 1
st.append(v)
if f == 0:
return False
if len(leaf) == 0:
return False
if all(leaf[0] == leaf[i] for i in range(len(leaf))):
if leaf[0] >= 2:
return True
return False
from copy import deepcopy
if len(g) == 1:
# 次数 3 の頂点 がパスをなすはず
# そのとなりを探索すればじゅうぶん（４通り）
dis = [inf] * n
dd = []
dd0 = []
for u in range(n):
if d[u] == 3:
dis[u] = 0
cnt = 0
for v in e[u]:
if d[v] == 3:
cnt += 1
if cnt == 1:
add = []
for v in e[u]:
if d[v] != 3:
add.append(v)
dd.append(add)
if cnt == 0:
dd0 = e[u]
if len(dd) >= 3:
no()
exit()
if len(dd) == 2:
for x in add[0]:
for y in add[1]:
e2 = deepcopy(e)
e2[x].append(y)
e2[y].append(x)
if check(e2):
yes()
exit()
no()
exit()
if len(dd0) == 3:
for x in dd0:
for y in dd0:
if x == y: continue
e2 = deepcopy(e)
e2[x].append(y)
e2[y].append(x)
if check(e2):
yes()
exit()
no()
exit()
no()
exit()
if len(g) == 2:
s0 = sum(d[i] for i in g[0])
if 2 * s0 == g[0]:
c = g[0]
p = g[1]
else:
c = g[1]
p = g[0]
# p は path である必要がある
if len(p) >= 2:
cnt = 0
for i in p:
if d[i] == 1:
cnt += 1
elif d[i] == 2:
pass
else:
no()
exit()
if cnt != 2:
no()
exit()
# 次数 3 の頂点が サイクル
# これに適当につなぐ
dis = [inf] * n
st = []
for u in range(n):
if d[u] == 3:
cnt = 0
dis[u] = 0
for v in e[u]:
if d[v] == 3:
cnt += 1
else:
st.append(v)
d[v] = 1
if cnt != 2:
no()
exit()
leaf = []
while st:
u = st.pop()
if len(e[u]) == 1:
leaf.append(dis[u])
continue
f = 0
for v in e[u]:
if dis[v] == -1:
f += 1
dis[v] = dis[u] + 1
st.append(v)
if f == 0:
no()
exit()
leaf.sort()
leaf[0] += len(p)
if all(leaf[0] == leaf[i] for i in range(n)):
if leaf[0] >= 2:
yes()
exit()
no()
exit()