結果
| 問題 |
No.3348 Tree Balance
|
| コンテスト | |
| ユーザー |
 Nzt3
|
| 提出日時 | 2025-11-11 23:01:39 |
| 言語 | PyPy3 (7.3.15) |
| 結果 |
RE
|
| 実行時間 | - |
| コード長 | 6,981 bytes |
| コンパイル時間 | 226 ms |
| コンパイル使用メモリ | 82,316 KB |
| 実行使用メモリ | 140,972 KB |
| 最終ジャッジ日時 | 2025-11-13 21:19:10 |
| 合計ジャッジ時間 | 11,988 ms |
|
ジャッジサーバーID （参考情報） |
judge2 / judge1 |
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| ファイルパターン | 結果 |
|---|---|
| other | AC * 23 RE * 2 |
ソースコード
import math
from collections import deque
from bisect import bisect_left, bisect_right
from typing import Generic, Iterable, Iterator, TypeVar
T = TypeVar('T')
class SortedSet(Generic[T]):
BUCKET_RATIO = 16
SPLIT_RATIO = 24
def __init__(self, a: Iterable[T] = []) -> None:
"Make a new SortedSet from iterable. / O(N) if sorted and unique / O(N log N)"
a = list(a)
n = len(a)
if any(a[i] > a[i + 1] for i in range(n - 1)):
a.sort()
if any(a[i] >= a[i + 1] for i in range(n - 1)):
a, b = [], a
for x in b:
if not a or a[-1] != x:
a.append(x)
n = self.size = len(a)
num_bucket = int(math.ceil(math.sqrt(n / self.BUCKET_RATIO)))
self.a = [a[n * i // num_bucket: n *
(i + 1) // num_bucket] for i in range(num_bucket)]
def __iter__(self) -> Iterator[T]:
for i in self.a:
for j in i:
yield j
def __reversed__(self) -> Iterator[T]:
for i in reversed(self.a):
for j in reversed(i):
yield j
def __eq__(self, other) -> bool:
return list(self) == list(other)
def __len__(self) -> int:
return self.size
def __repr__(self) -> str:
return "SortedSet" + str(self.a)
def __str__(self) -> str:
s = str(list(self))
return "{" + s[1: len(s) - 1] + "}"
def _position(self, x: T) -> tuple[list[T], int, int]:
"return the bucket, index of the bucket and position in which x should be. self must not be empty."
for i, a in enumerate(self.a):
if x <= a[-1]:
break
return (a, i, bisect_left(a, x))
def __contains__(self, x: T) -> bool:
if self.size == 0:
return False
a, _, i = self._position(x)
return i != len(a) and a[i] == x
def add(self, x: T) -> bool:
"Add an element and return True if added. / O(√N)"
if self.size == 0:
self.a = [[x]]
self.size = 1
return True
a, b, i = self._position(x)
if i != len(a) and a[i] == x:
return False
a.insert(i, x)
self.size += 1
if len(a) > len(self.a) * self.SPLIT_RATIO:
mid = len(a) >> 1
self.a[b:b+1] = [a[:mid], a[mid:]]
return True
def _pop(self, a: list[T], b: int, i: int) -> T:
ans = a.pop(i)
self.size -= 1
if not a:
del self.a[b]
return ans
def discard(self, x: T) -> bool:
"Remove an element and return True if removed. / O(√N)"
if self.size == 0:
return False
a, b, i = self._position(x)
if i == len(a) or a[i] != x:
return False
self._pop(a, b, i)
return True
def lt(self, x: T) -> T | None:
"Find the largest element < x, or None if it doesn't exist."
for a in reversed(self.a):
if a[0] < x:
return a[bisect_left(a, x) - 1]
def le(self, x: T) -> T | None:
"Find the largest element <= x, or None if it doesn't exist."
for a in reversed(self.a):
if a[0] <= x:
return a[bisect_right(a, x) - 1]
def gt(self, x: T) -> T | None:
"Find the smallest element > x, or None if it doesn't exist."
for a in self.a:
if a[-1] > x:
return a[bisect_right(a, x)]
def ge(self, x: T) -> T | None:
"Find the smallest element >= x, or None if it doesn't exist."
for a in self.a:
if a[-1] >= x:
return a[bisect_left(a, x)]
def __getitem__(self, i: int) -> T:
"Return the i-th element."
if i < 0:
for a in reversed(self.a):
i += len(a)
if i >= 0:
return a[i]
else:
for a in self.a:
if i < len(a):
return a[i]
i -= len(a)
raise IndexError
def pop(self, i: int = -1) -> T:
"Pop and return the i-th element."
if i < 0:
for b, a in enumerate(reversed(self.a)):
i += len(a)
if i >= 0:
return self._pop(a, ~b, i)
else:
for b, a in enumerate(self.a):
if i < len(a):
return self._pop(a, b, i)
i -= len(a)
raise IndexError
def index(self, x: T) -> int:
"Count the number of elements < x."
ans = 0
for a in self.a:
if a[-1] >= x:
return ans + bisect_left(a, x)
ans += len(a)
return ans
def index_right(self, x: T) -> int:
"Count the number of elements <= x."
ans = 0
for a in self.a:
if a[-1] > x:
return ans + bisect_right(a, x)
ans += len(a)
return ans
def main():
N = int(input())
W = list(map(int, input().split()))
G = [[] for _ in range(N)]
for _ in range(N - 1):
U, V = map(int, input().split())
U -= 1
V -= 1
G[U].append(V)
G[V].append(U)
subtree = W[:]
par = [-1] * N
def dfs_subtree(v, p):
par[v] = p
for u in G[v]:
if u != p:
subtree[v] += dfs_subtree(u, v)
return subtree[v]
dfs_subtree(0, -1)
gr = 0
# 重心探索
while True:
br = True
for u in G[gr]:
if u == par[gr]:
continue
if subtree[u] * 2 >= subtree[0]:
gr = u
br = False
break
if br:
break
# 重心を根として部分木サイズを再計算
subtree = W[:]
dfs_subtree(gr, -1)
ans = subtree[gr]
cut1 = SortedSet[int]()
for s in G[gr]:
bfs = deque([s])
d = []
while bfs:
v = bfs.popleft()
d.append(subtree[v])
for u in G[v]:
if u != par[v]:
bfs.append(u)
# 異なる部分木を切る場合 S1 - S2(G) - S3
for w in d:
mid = (subtree[gr] - w + 1) // 2
it = cut1.ge(mid)
if it:
ans = min(
ans, max(it, w, subtree[gr] - w - it) - min(it, w, subtree[gr] - w - it))
it = cut1.le(mid)
if it:
ans = min(
ans, max(it, w, subtree[gr] - w - it) - min(it, w, subtree[gr] - w - it))
# 同じ部分木を2つに分ける場合 S1(G) - S2 - S3
for w in d:
ans = min(ans, max(subtree[gr] - subtree[s], w, subtree[s] - w)
- min(subtree[gr] - subtree[s], w, subtree[s] - w))
for w in d:
cut1.add(w)
print(ans)
if __name__ == "__main__":
main()