結果

問題 No.2892 Lime and Karin
ユーザー adapchiadapchi
提出日時 2024-09-13 23:31:20
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 3,936 ms / 8,000 ms
コード長 1,395 bytes
コンパイル時間 360 ms
コンパイル使用メモリ 82,304 KB
実行使用メモリ 144,400 KB
最終ジャッジ日時 2024-09-13 23:33:00
合計ジャッジ時間 96,227 ms
ジャッジサーバーID
(参考情報)
judge1 / judge3
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 52
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 #
プレゼンテーションモードにする

N = int(input())
G = [[] for _ in range(N)]
for _ in range(N - 1):
u, v = [int(x) - 1 for x in input().split()]
G[u].append(v)
G[v].append(u)
S = [1 if x == '1' else -1 for x in input()]
used = [False] * N
size = [0] * N
def centroid(x):
stk = [(x, None, 0)]
while stk:
u, p, t = stk.pop()
if t == 0:
stk.append((u, p, 1))
stk.extend((v, u, 0) for v in G[u] if not used[v] and v != p)
else:
size[u] = 1 + sum(size[v] for v in G[u] if not used[v] and v != p)
p = None
s = size[x]
while True:
y = next((y for y in G[x] if not used[y] and y != p and size[y] * 2 > s), None)
if y is None: break
x, p = y, x
return x
def paths(x, p):
stk = [(x, p, S[x])]
res = []
while stk:
u, p, d = stk.pop()
res.append(d)
stk.extend((v, u, d + S[v]) for v in G[u] if not used[v] and v != p)
return res
def pairs(xs, y):
xs.sort()
res = 0
i = len(xs)
for x in xs:
while i >= 1 and x + xs[i - 1] + y > 0:
i -= 1
res += len(xs) - i
return res
stk = [0]
ans = 0
while stk:
u = centroid(stk.pop())
if S[u] == 1: ans += 1
vs = [v for v in G[u] if not used[v]]
stk.extend(vs)
ds = [paths(v, u) for v in vs]
ans += sum(sum(x + S[u] > 0 for x in d) for d in ds)
ans += (pairs(sum(ds, start=[]), S[u]) - sum(pairs(d, S[u]) for d in ds)) // 2
used[u] = True
print(ans)
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