結果

問題 No.1400 すごろくで世界旅行
ユーザー gew1fw
提出日時 2025-06-12 15:54:50
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 317 ms / 3,153 ms
コード長 2,562 bytes
コンパイル時間 181 ms
コンパイル使用メモリ 82,780 KB
実行使用メモリ 113,676 KB
最終ジャッジ日時 2025-06-12 15:54:54
合計ジャッジ時間 2,909 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge5
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 * 18
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 # 

import sys
from collections import deque

def main():
    V, D = map(int, sys.stdin.readline().split())
    E = [sys.stdin.readline().strip() for _ in range(V)]
    
    # Build adjacency list
    adj = [[] for _ in range(V)]
    for i in range(V):
        for j in range(V):
            if E[i][j] == '1':
                adj[i].append(j)
    
    # Check if the graph is connected
    visited = [False] * V
    queue = deque([0])
    visited[0] = True
    while queue:
        u = queue.popleft()
        for v in adj[u]:
            if not visited[v]:
                visited[v] = True
                queue.append(v)
    if not all(visited):
        print("No")
        return
    
    # Check for self-loop
    has_self_loop = any(E[i][i] == '1' for i in range(V))
    
    # Function to perform BFS and return farthest node and max distance
    def bfs(u):
        dist = [-1] * V
        dist[u] = 0
        q = deque([u])
        while q:
            current = q.popleft()
            for neighbor in adj[current]:
                if dist[neighbor] == -1:
                    dist[neighbor] = dist[current] + 1
                    q.append(neighbor)
        max_dist = max(dist)
        far_node = dist.index(max_dist)
        return far_node, max_dist
    
    if has_self_loop:
        # Find diameter using two BFS passes
        u, _ = bfs(0)
        v, diameter = bfs(u)
        if D >= diameter:
            print("Yes")
        else:
            print("No")
    else:
        # Check if the graph is bipartite
        is_bipartite = True
        color = [-1] * V
        for start in range(V):
            if color[start] == -1:
                queue = deque([start])
                color[start] = 0
                while queue:
                    u = queue.popleft()
                    for v in adj[u]:
                        if color[v] == -1:
                            color[v] = color[u] ^ 1
                            queue.append(v)
                        elif color[v] == color[u]:
                            is_bipartite = False
                            break
                    if not is_bipartite:
                        break
                if not is_bipartite:
                    break
        if is_bipartite:
            print("No")
            return
        else:
            # Find diameter using two BFS passes
            u, _ = bfs(0)
            v, diameter = bfs(u)
            if D >= diameter:
                print("Yes")
            else:
                print("No")

if __name__ == "__main__":
    main()
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