{"problem":{"name":"树的直径","description":{"content":"给定一棵 $n$ 个结点的树，树没有边权。请求出树的直径是多少，即树上最长的不重复经过一个点的路径长度是多少。","description_type":"Markdown"},"platform":"Luogu","limit":{"time_limit":1000,"memory_limit":131072},"difficulty":{"LuoguStyle":"P3"},"is_remote":true,"is_sync":true,"sync_url":null,"sign":"LGB4016"},"statements":[{"statement_type":"Markdown","content":"给定一棵 $n$ 个结点的树，树没有边权。请求出树的直径是多少，即树上最长的不重复经过一个点的路径长度是多少。\n\n## Input\n\n第一行输入一个正整数 $n$，表示结点个数。\n\n第二行开始，往下一共 $n-1$ 行，每一行两个正整数 $(u,v)$，表示一条边。\n\n## Output\n\n输出一行，表示树的直径是多少。\n\n[samples]\n\n## Note\n\n数据保证，$1 \\leq n \\leq 10^5$。","is_translate":false,"language":"English"}],"meta":{"iden":"LGB4016","tags":["O2优化","深度优先搜索 DFS","树形 DP","树的直径"],"sample_group":[["5\n1 2\n2 4\n4 5\n2 3","3"]],"created_at":"2026-03-03 11:09:25"}}