Tag: floyd warshall

from collections import defaultdict, deque

N, M = map(int, input().split())

taller = defaultdict(list)
shorter = defaultdict(list)

for _ in range(M):
    a, b = map(int, input().split())
    taller[a].append(b)
    shorter[b].append(a)

def bfs(graph, start):
    visited = set()
    q = deque([start])
    while q:
        node = q.popleft()
        for n in graph[node]:
            if n not in visited:
                visited.add(n)
                q.append(n)
    return visited

result = 0
for i in range(1, N+1):
    visited_taller = bfs(taller, i)
    visited_shorter = bfs(shorter, i)
    # 앞 뒤의 키를 모두 탐색 가능할 경우
    if len(visited_taller) + len(visited_shorter) == N - 1:
        result += 1

print(result)

from collections import defaultdict, deque

INF = float('inf')

def floyd(n, dist_list):
    for k in range(n):
        for i in range(n):
            for j in range(n):
                dist_list[i][j] = min(dist_list[i][j], dist_list[i][k] + dist_list[k][j])

    min_sum = INF
    result = 0
    for i, sum_dist in enumerate(map(sum, dist_list), start=1):
        if min_sum > sum_dist:
            min_sum = sum_dist
            result = i

    return result

def main():
    N, M = map(int, input().split())

    dist_list = [[INF] * N for _ in range(N)]
    for i in range(0, N):
        dist_list[i][i] = 0

    for _ in range(M):
        a, b = map(int, input().split())
        a -= 1
        b -= 1
        dist_list[a][b] = 1
        dist_list[b][a] = 1
    
    print(floyd(N, dist_list))


if __name__ == "__main__":
    main()

INF = float("inf")


def floyd(n, dist_list):
    """플로이드 워셜"""

    for k in range(1, n + 1):
        for i in range(1, n + 1):
            for j in range(1, n + 1):
                dist_list[i][j] = min(
                    dist_list[i][j], dist_list[i][k] + dist_list[k][j]
                )

    return dist_list


def print_result(dist_list):
    """결과 출력"""
    for dist in dist_list[1:]:
        for d in dist[1:]:
            print(d if d != INF else 0, end=" ")
        print()


def main():
    n = int(input())
    m = int(input())

    dist_list = [[INF] * (n + 1) for _ in range(n + 1)]

    for _ in range(m):
        a, b, c = map(int, input().split())
        dist_list[a][b] = min(dist_list[a][b], c)

    for i in range(1, n + 1):
        dist_list[i][i] = 0

    dist_list = floyd(n, dist_list)
    print_result(dist_list)


if __name__ == "__main__":
    main()