結果

問題 No.3291 K-step Navigation
ユーザー detteiuu
提出日時 2025-10-06 21:43:03
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 1,409 ms / 3,000 ms
コード長 2,834 bytes
コンパイル時間 301 ms
コンパイル使用メモリ 82,640 KB
実行使用メモリ 99,880 KB
最終ジャッジ日時 2025-10-06 21:43:17
合計ジャッジ時間 12,956 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge2
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ファイルパターン 結果
sample AC * 2
other AC * 51
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 # 

from collections import deque, defaultdict

class UnionFind:
    def __init__(self,n):
        self.n = n
        self.parent_size = [-1]*n
 
    def leader(self,a):
        if self.parent_size[a] < 0:
            return a
        self.parent_size[a] = self.leader(self.parent_size[a])
        return self.parent_size[a]
 
    def merge(self,a,b):
        x, y = self.leader(a), self.leader(b)
        if x == y:
            return 
        if abs(self.parent_size[x]) < abs(self.parent_size[y]):
            x, y = y, x
        self.parent_size[x] += self.parent_size[y]
        self.parent_size[y] = x
        return 
 
    def same(self,a,b):
        return self.leader(a) == self.leader(b)
 
    def size(self,a):
        return abs(self.parent_size[self.leader(a)])
 
    def groups(self):
        result = [[] for _ in range(self.n)]
        for i in range(self.n):
            result[self.leader(i)].append(i)
        return result

def encode(n, d):
    return n*2+d
def decode(n):
    return n//2, n%2

INF = 1<<60

N, M, K, S, T = map(int, input().split())
G = [[] for _ in range(N)]
for _ in range(M):
    u, v = map(int, input().split())
    u, v = u-1, v-1
    G[u].append(v)
    G[v].append(u)

S, T = S-1, T-1

visited = [-1]*N
visited[S] = 0
que = deque()
que.append(S)
while que:
    n = que.popleft()
    for v in G[n]:
        if visited[v] == -1:
            visited[v] = visited[n]+1
            que.append(v)
    
if K <= visited[T]:
    exit(print("Yes"))

UF = UnionFind(N)
for i in range(N):
    for v in G[i]:
        UF.merge(i, v)

if visited[T] == -1 and UF.size(S) == UF.size(T) == 1 and K%2 == 0:
    print("No")
elif UF.size(S) == 2 and UF.same(S, T) and K%2 == 0:
    if N == 2:
        print("No")
    else:
        MIN = INF
        groups = UF.groups()
        for i in range(N):
            if i == S or i == T:
                continue
            if UF.leader(i) != i:
                continue
            for j in groups[i]:
                visited = defaultdict(lambda: -1)
                visited[encode(j, 0)] = 0
                que = deque()
                que.append(encode(j, 0))
                flag = False
                while que:
                    n, d = decode(que.popleft())
                    for v in G[n]:
                        if visited[encode(v, d^1)] == -1:
                            visited[encode(v, d^1)] = visited[encode(n, d)]+1
                            if v == j and d^1 == 1:
                                MIN = min(MIN, visited[encode(v, d^1)])
                                flag = True
                                break
                            que.append(encode(v, d^1))
                    if flag:
                        break
        if MIN+2+1 <= K:
            print("Yes")
        else:
            print("No")
else:
    print("Yes")
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