Bellman-Ford Algorithm벨만-포드

def bellman_ford(vertices, edges, start):
    dist = {v: float('inf') for v in vertices}
    dist[start] = 0

    # V-1번 반복
    for _ in range(len(vertices) - 1):
        for u, v, w in edges:
            if dist[u] + w < dist[v]:
                dist[v] = dist[u] + w

    # 음수 사이클 탐지
    for u, v, w in edges:
        if dist[u] + w < dist[v]:
            return None  # 음수 사이클 존재
    return dist

vertices = ['A','B','C','D','E']
edges = [('A','B',4),('A','C',2),('B','C',-3),('C','D',2),('D','E',3)]
print(bellman_ford(vertices, edges, 'A'))