結果

問題 No.3206 う　し　た　ウ　ニ　木　あ　く　ん　笑
ユーザー lif4635
提出日時 2025-07-18 22:07:40
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 1,242 ms / 3,000 ms
コード長 3,817 bytes
コンパイル時間 235 ms
コンパイル使用メモリ 82,376 KB
実行使用メモリ 213,036 KB
最終ジャッジ日時 2025-07-18 22:07:57
合計ジャッジ時間 15,097 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge5
このコードへのチャレンジ
（要ログイン）
ファイルパターン 結果
sample AC * 2
other AC * 30
権限があれば一括ダウンロードができます

ソースコード

diff # 

# input
import sys
input = sys.stdin.readline
II = lambda : int(input())
MI = lambda : map(int, input().split())
LI = lambda : [int(a) for a in input().split()]
SI = lambda : input().rstrip()
LLI = lambda n : [[int(a) for a in input().split()] for _ in range(n)]
LSI = lambda n : [input().rstrip() for _ in range(n)]
MI_1 = lambda : map(lambda x:int(x)-1, input().split())
LI_1 = lambda : [int(a)-1 for a in input().split()]

def graph(n:int, m:int, dir:bool=False, index:int=-1) -> list[set[int]]:
    edge = [set() for i in range(n+1+index)]
    for _ in range(m):
        a,b = map(int, input().split())
        a += index
        b += index
        edge[a].add(b)
        if not dir:
            edge[b].add(a)
    return edge

def graph_w(n:int, m:int, dir:bool=False, index:int=-1) -> list[set[tuple]]:
    edge = [set() for i in range(n+1+index)]
    for _ in range(m):
        a,b,c = map(int, input().split())
        a += index
        b += index
        edge[a].add((b,c))
        if not dir:
            edge[b].add((a,c))
    return edge

mod = 998244353
inf = 1001001001001001001
ordalp = lambda s : ord(s)-65 if s.isupper() else ord(s)-97
ordallalp = lambda s : ord(s)-39 if s.isupper() else ord(s)-97
yes = lambda : print("Yes")
no = lambda : print("No")
yn = lambda flag : print("Yes" if flag else "No")
def acc(a:list[int]):
    sa = [0]*(len(a)+1)
    for i in range(len(a)):
        sa[i+1] = a[i] + sa[i]
    return sa

prinf = lambda ans : print(ans if ans < 1000001001001001001 else -1)
alplow = "abcdefghijklmnopqrstuvwxyz"
alpup = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
alpall = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
URDL = {'U':(-1,0), 'R':(0,1), 'D':(1,0), 'L':(0,-1)}
DIR_4 = [[-1,0],[0,1],[1,0],[0,-1]]
DIR_8 = [[-1,0],[-1,1],[0,1],[1,1],[1,0],[1,-1],[0,-1],[-1,-1]]
DIR_BISHOP = [[-1,1],[1,1],[1,-1],[-1,-1]]
prime60 = [2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59]
sys.set_int_max_str_digits(0)
# sys.setrecursionlimit(10**6)
# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')

from collections import defaultdict,deque
from heapq import heappop,heappush
from bisect import bisect_left,bisect_right
DD = defaultdict
BSL = bisect_left
BSR = bisect_right

n = II()

edge = graph(n, n-1)

def dfs(p):
    st = [p]
    par = [-1] * n
    dis = [0] * n
    while st:
        u = st.pop()
        for v in edge[u]:
            if par[u] == v: continue
            par[v] = u
            dis[v] = dis[u] + 1 
            st.append(v)
    return dis

dis = dfs(0)
root = dis.index(max(dis))
dis = dfs(root)
root2 = dis.index(max(dis))

# 葉がウニからの距離が等しい
def calc(root):
    ans = 0
    st = [~root, root]
    par = [-1] * n
    dis = [0] * n
    dp = [[0] for i in range(n)]
    sub = [-1] * n
    ma = [-1] * n
    while st:
        u = st.pop()
        if u >= 0:
            for v in edge[u]:
                if par[u] == v: continue
                par[v] = u
                dis[v] = dis[u] + 1 
                st.append(~v)
                st.append(v)
                if u == root:
                    sub[v] = v
                else:
                    sub[v] = sub[u]
        else:
            u = ~u
            ma[u] = max(dp[u])
            if u != root:
                dp[par[u]].append(ma[u] + 1)

    s = dp[root].copy()
    s.sort(reverse=True)

    ans = 0
    for u in range(n):
        # print(dp[u])
        if u != root:
            k = ma[sub[u]] + 1# 自分の子孫で最も大きい
            if s[0] == k:
                dp[u].append(dis[u] + s[1])
            else:
                dp[u].append(dis[u] + s[0])
        
        dp[u].sort(reverse=True)
        # print(u, dp[u])
        for i in range(len(dp[u])):
            ans = max(ans, 1 + (i+1) * dp[u][i])
    return ans


print(max(calc(root), calc(root2)))
0