結果

問題 No.2674 k-Walk on Bipartite
ユーザー lam6er
提出日時 2025-03-26 15:47:32
言語 PyPy3
(7.3.15)
結果
WA  
実行時間 -
コード長 1,971 bytes
コンパイル時間 161 ms
コンパイル使用メモリ 82,420 KB
実行使用メモリ 125,180 KB
最終ジャッジ日時 2025-03-26 15:48:30
合計ジャッジ時間 6,574 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 24 WA * 12
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ソースコード

diff #
プレゼンテーションモードにする

import sys
from collections import deque
def main():
    input = sys.stdin.read().split()
    ptr = 0
    N = int(input[ptr])
    ptr += 1
    M = int(input[ptr])
    ptr += 1
    s = int(input[ptr]) - 1  # 0-based
    ptr += 1
    t = int(input[ptr]) - 1
    ptr += 1
    k = int(input[ptr])
    ptr += 1
    edges = [[] for _ in range(N)]
    for _ in range(M):
        a = int(input[ptr]) - 1
        ptr += 1
        b = int(input[ptr]) - 1
        ptr += 1
        edges[a].append(b)
        edges[b].append(a)
    # Bipartition coloring
    color = [-1] * N
    is_bipartite = True
    for start in range(N):
        if color[start] == -1:
            q = deque()
            q.append(start)
            color[start] = 0
            while q:
                u = q.popleft()
                for v in edges[u]:
                    if color[v] == -1:
                        color[v] = color[u] ^ 1
                        q.append(v)
                    elif color[v] == color[u]:
                        is_bipartite = False
    # Since F is guaranteed to be bipartite, we don't need to handle non-bipartite case
    s_color = color[s]
    t_color = color[t]
    # Check parity
    if (s_color == t_color and k % 2 != 0) or (s_color != t_color and k % 2 != 1):
        print("No")
        return
    # Check connectivity and compute shortest distance d from s to t
    visited = [False] * N
    dist = [-1] * N
    q = deque()
    q.append(s)
    dist[s] = 0
    visited[s] = True
    found = False
    while q:
        u = q.popleft()
        if u == t:
            found = True
            break
        for v in edges[u]:
            if not visited[v]:
                visited[v] = True
                dist[v] = dist[u] + 1
                q.append(v)
    if not found:
        print("Unknown")
        return
    d = dist[t]
    if d > k or (k - d) % 2 != 0:
        print("Unknown")
    else:
        print("Yes")
if __name__ == "__main__":
    main()
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