[백준] 1504번 특정한 최단 경로 (파이썬)

https://www.acmicpc.net/problem/1504

import sys
import heapq

input = sys.stdin.readline

n, e = map(int, input().split())
graph = [[] for _ in range(n+1)]
for _ in range(e):
    a, b, c = map(int, input().split())
    graph[a].append((b, c))
    graph[b].append((a, c))
v1, v2 = map(int, input().split())

INF = float('inf')

def dijkstra(start, end):
    distance = [INF]*(n+1)
    
    q = []
    heapq.heappush(q, (0, start))
    distance[start] = 0
    
    while q:
        dist, now = heapq.heappop(q)
        if distance[now] < dist:
            continue
            
        for i in graph[now]:
            cost = dist + i[1]
            if cost < distance[i[0]]:
                distance[i[0]] = cost
                heapq.heappush(q, (cost, i[0]))
                
    return distance[end]

route1 = dijkstra(1, v1) + dijkstra(v1, v2) + dijkstra(v2, n)
route2 = dijkstra(1, v2) + dijkstra(v2, v1) + dijkstra(v1, n)
result = min(route1, route2)
if result < INF:
    print(result)
else:
    print(-1)