Tietoverkko

import math

l = int(input())

speed_lookup = [[0] * l for i in range(l)]

for i in range(l - 1):
    a, b, x = map(int, input().split(' '))
    speed_lookup[a - 1][b - 1] = x
    speed_lookup[b - 1][a - 1] = x


def find_lowest(unvisited, distances):
    smallest_key, smallest_value = 0, math.inf
    for key in unvisited:
        value = distances[key]
        if value < smallest_value:
            smallest_key = key
    return smallest_key


def speeds_for(initial):
    unvisited = list(range(l))
    distance = [0 if i == initial else math.inf for i in unvisited]
    speeds = [math.inf for _ in unvisited]
    unvisited.remove(initial)

    current = initial

    speed_counter = 0

    while True:
        current_distance = distance[current]
        current_speed = speeds[current]

        for j in unvisited:
            speed = speed_lookup[j][current]
            if speed == 0:
                continue

            distance[j] = current_distance + 1
            min_speed = min(current_speed, speed)
            speeds[j] = min_speed
            speed_counter += min_speed

        if len(unvisited) == 0:
            break

        current = find_lowest(unvisited, distance)
        unvisited.remove(current)

    return speed_counter


total_speed = 0
for i in range(l):
    total_speed += speeds_for(i)

print(int(total_speed / 2))

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 2, 3

Verdict: TIME LIMIT EXCEEDED

Test 3

Group: 3

Verdict: RUNTIME ERROR