[백준] 1167번 트리의 지름 (파이썬)

1167번: 트리의 지름

 

코드

import heapq
import sys

v = int(input())
li = [[] for _ in range(v+1)]
for _ in range(v):
    input_li = list(map(int, input().split(" ")))
    for i in range(1, len(input_li)-1,2):
        node = input_li[i]
        length = input_li[i+1]
        li[input_li[0]].append([node, length])

INF = sys.maxsize
def dikstra(start):
    destination = [INF] * (v+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

d1 = dikstra(1)

print(max(dikstra(d1.index(max(d1[1:])))[1:]))