[BOJ] 백준 1967번 - 트리의 지름 (Python)

문제

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해결

import sys
sys.setrecursionlimit(10 ** 9)

def dfs(s, sw):
  for n, nw in graph[s]:
    if visited[n] == -1:
      visited[n] = sw + nw
      dfs(n, sw + nw)

n = int(input())
graph = [[] for _ in range(n + 1)]
visited = [-1] * (n + 1)

for _ in range(n-1):
  a, b, cost = map(int, input().split())
  graph[a].append((b, cost))
  graph[b].append((a, cost))

start = visited.index(max(visited))

visited = [-1] * (n + 1)
visited[1] = 0
dfs(1, 0)

start = visited.index(max(visited))

visited = [-1] * (n + 1)
visited[start] = 0
dfs(start, 0)

print(max(visited))