結果

問題 No.3113 The farthest point
ユーザー lif4635
提出日時 2025-04-18 20:45:13
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 646 ms / 2,000 ms
コード長 3,064 bytes
コンパイル時間 499 ms
コンパイル使用メモリ 81,912 KB
実行使用メモリ 146,876 KB
最終ジャッジ日時 2025-04-18 20:45:27
合計ジャッジ時間 13,110 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge5
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ファイルパターン 結果
sample AC * 3
other AC * 33
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_w(n, n-1)

def dfs(start):
    dis = [inf] * n
    dis[start] = 0
    mdis = [-inf] * n # 最大の重みを見ておく
    que = [~start, start]
    par = [-1] * n
    ans = 0
    while que:
        u = que.pop()
        if u >= 0:
            for v, w in edge[u]:
                if par[u] == v: continue
                dis[v] = dis[u] + w
                que.append(~v)
                que.append(v)
                par[v] = u
        else:
            u = ~u
            use = [dis[u]]
            for v, w in edge[u]:
                if par[u] == v: continue
                use.append(mdis[v])
            use.sort()
            if len(use) >= 2:
                ans = max(ans, use[-1] + use[-2] - 2 * dis[u])
            mdis[u] = use[-1]
            # print(use)
    # print(dis,mdis)
    return ans

dis = dfs(0)
print(dis)
0