[백준] 1967번 트리의 지름 (파이썬)

1967번: 트리의 지름

 

 

코드

import heapq
import sys

n = int(input())
li = [[] for _ in range(n+1)]
for _ in range(n-1):
    a, b, weight = map(int, input().split(" "))
    li[a].append([b,weight])
    li[b].append([a,weight])

INF = sys.maxsize
def dikstra(start):
    destination = [INF] * (n+1)
    destination[start] = 0
    heap = []
    heapq.heappush(heap, [destination[start], start])
    while heap:
        weight, node = heapq.heappop(heap)
        for next_node, next_weight in li[node]:
            new_weight = weight + next_weight
            if new_weight < destination[next_node]:
                destination[next_node] = new_weight
                heapq.heappush(heap, [new_weight, next_node])
    
    return destination

destination = dikstra(1)
print(max(dikstra(destination.index(max(destination[1:])))[1:]))