Buggy python submission (verdict: Runtime Error):
import heapq
from itertools import permutations
n, m, r = map(int, input().split())
R = list(map(lambda x: int(x)-1, input().split()))
edges = [[]for _ in range(n)]
for _ in range(m):
    a, b, c = map(int, input().split())
    edges[a].append((c, b-1))
    edges[b].append((c, a-1))


def dijkstra(init_v):
    next_v = [(0, init_v)]
    INF = 10**18
    dist = [INF]*n
    dist[init_v] = 0
    while next_v:
        d, v = heapq.heappop(next_v)
        if dist[v] < d:
            continue
        for d, v2 in edges[v]:
            if dist[v2] <= dist[v]+d:
                continue
            dist[v2] = dist[v]+d
            heapq.heappush(next_v, (dist[v2], v2))
    return dist


dists = []
for x in R:
    dist = dijkstra(x)
    dists.append(dist)

INF = 10**18
ans = INF
for subset in permutations(range(r)):
    d = 0
    for v, v2 in zip(subset, subset[1:]):
        d += dists[v][R[v2]]
    if d < ans:
        ans = d

print(ans)


Fixed submission:
import heapq
from itertools import permutations
n, m, r = map(int, input().split())
R = list(map(lambda x: int(x)-1, input().split()))
edges = [[]for _ in range(n)]
for _ in range(m):
    a, b, c = map(int, input().split())
    a -= 1
    b -= 1
    edges[a].append((c, b))
    edges[b].append((c, a))


def dijkstra(init_v):
    next_v = [(0, init_v)]
    INF = 10**18
    dist = [INF]*n
    dist[init_v] = 0
    while next_v:
        d, v = heapq.heappop(next_v)
        if dist[v] < d:
            continue
        for d, v2 in edges[v]:
            if dist[v2] <= dist[v]+d:
                continue
            dist[v2] = dist[v]+d
            heapq.heappush(next_v, (dist[v2], v2))
    return dist


dists = []
for x in R:
    dist = dijkstra(x)
    dists.append(dist)

INF = 10**18
ans = INF
for subset in permutations(range(r)):
    d = 0
    for v, v2 in zip(subset, subset[1:]):
        d += dists[v][R[v2]]
    if d < ans:
        ans = d

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from itertools import permutations
n, m, r = map(int, input().split())
R = list(map(lambda x: int(x)-1, input().split()))
INF = 10**18
dist = [[INF]*n for _ in range(n)]
for _ in range(m):
    a, b, c = map(int, input().split())
    dist[a-1][b-1] = c
    dist[b-1][a-1] = c

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

ans = INF
for subset in permutations(R):
    d = 0
    for v, v2 in zip(subset, subset[1:]):
        d += dist[v][v2]
    if d < ans:
        ans = d
print(ans)


Fixed submission:
import heapq
from itertools import permutations
n, m, r = map(int, input().split())
R = list(map(lambda x: int(x)-1, input().split()))
edges = [[]for _ in range(n)]
for _ in range(m):
    a, b, c = map(int, input().split())
    a -= 1
    b -= 1
    edges[a].append((c, b))
    edges[b].append((c, a))


def dijkstra(init_v):
    next_v = [(0, init_v)]
    INF = 10**18
    dist = [INF]*n
    dist[init_v] = 0
    while next_v:
        d, v = heapq.heappop(next_v)
        if dist[v] < d:
            continue
        for d, v2 in edges[v]:
            if dist[v2] <= dist[v]+d:
                continue
            dist[v2] = dist[v]+d
            heapq.heappush(next_v, (dist[v2], v2))
    return dist


dists = []
for x in R:
    dist = dijkstra(x)
    dists.append(dist)

INF = 10**18
ans = INF
for subset in permutations(range(r)):
    d = 0
    for v, v2 in zip(subset, subset[1:]):
        d += dists[v][R[v2]]
    if d < ans:
        ans = d

print(ans)