結果

問題 No.3031 曲面の向き付け
ユーザー kidodesu
提出日時 2025-02-21 22:36:37
言語 PyPy3
(7.3.15)
結果
WA  
実行時間 -
コード長 2,042 bytes
コンパイル時間 999 ms
コンパイル使用メモリ 82,856 KB
実行使用メモリ 262,056 KB
最終ジャッジ日時 2025-02-21 22:36:44
合計ジャッジ時間 6,614 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge4
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ファイルパターン 結果
sample AC * 4
other AC * 6 WA * 1 TLE * 1 -- * 21
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

from collections import deque
def scc(N, G, RG):
    order = []
    used = [0]*N
    def dfs(s):
        used[s] = 1
        for t in G[s]:
            if not used[t]:
                dfs(t)
        order.append(s)
    for i in range(N):
        if not used[i]:
            dfs(i)
    group = [-1]*N
    label = 0
    order.reverse()
    for s in order:
        if group[s] != -1:
            continue
        que = deque([s])
        group[s] = label
        while que:
            v = que.popleft()
            for w in RG[v]:
                if group[w] != -1:
                    continue
                que.append(w)
                group[w] = label
        label += 1
    return group # topological ordering
N = int(input())
G = [[] for i in range(2*N)]
RG = [[] for i in range(2*N)]
tri = [tuple(map(int, input().split())) for _ in range(N)]
from collections import defaultdict
dict = defaultdict(lambda:[])
def add_edge(i, neg_i, j, neg_j):
    if neg_i:
        i0 = i+N; i1 = i
    else:
        i0 = i; i1 = i+N
    if neg_j:
        j0 = j+N; j1 = j
    else:
        j0 = j; j1 = j+N
    # add (~a ⇒ b)
    G[i1].append(j0); RG[j0].append(i1)
    # add (~b ⇒ a)
    G[j1].append(i0); RG[i0].append(j1)
for i in range(N):
    a, b, c = tri[i]
    for u, v in [(a, b), (b, c)]:
        dict[(u, v)].append((i, 1))
    dict[(a, c)].append((i, 0))
    for u, v in dict:
        if len(dict[(u, v)]) >= 3:
            print("NO")
            exit()
        elif len(dict[(u, v)]) == 2:
            i0, t0 = dict[(u, v)][0]
            i1, t1 = dict[(u, v)][1]
            if t0 == t1:
                add_edge(i0, True, i1, False)
                add_edge(i0, False, i1, True)
            else:
                add_edge(i0, True, i1, True)
                add_edge(i0, False, i1, False)
group = scc(2*N, G, RG)
# check if the formula is satisfiable
def check(group):
    for i in range(N):
        if group[i] == group[i+N]:
            return False
    return True
if check(group):
    print("YES")
else:
    print("NO")
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