結果

問題 No.3272 Separate Contractions
コンテスト
ユーザー apricity
提出日時 2025-08-10 17:51:45
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 1,805 ms / 3,000 ms
コード長 3,144 bytes
コンパイル時間 340 ms
コンパイル使用メモリ 82,660 KB
実行使用メモリ 351,036 KB
最終ジャッジ日時 2025-09-11 00:35:30
合計ジャッジ時間 33,953 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge2
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 * 3
other AC * 43
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 # 

from collections import deque
__import__("sys").setrecursionlimit(1000000)

def get_dist(N, G, start):
    dist = [-1 for _ in range(N)]
    dist[start] = 0
    q = deque()
    q.append(start)
    while len(q) > 0:
        x = q.popleft()
        for y in G[x]:
            if dist[y] == -1:
                dist[y] = dist[x] + 1
                q.append(y)
    return dist

def get_center(N, G):
    dist = get_dist(N, G, 0)

    max_dist, argmax = -1, -1
    for i, dist_i in enumerate(dist):
        if max_dist < dist_i:
            max_dist, argmax = dist_i, i

    dist = get_dist(N, G, argmax)
    pre = [-1 for _ in range(N)]
    for i in range(N):
        for j in G[i]:
            if dist[j] == dist[i] - 1:
                pre[i] = j

    max_dist, argmax = -1, -1
    for i, dist_i in enumerate(dist):
        if max_dist < dist_i:
            max_dist, argmax = dist_i, i

    path = []
    cur = argmax
    while cur != -1:
        path.append(cur)
        cur = pre[cur]

    if max_dist % 2:
        return max_dist, path[max_dist//2], path[max_dist//2+1]
    else:
        return max_dist, path[max_dist//2], -1


def solve(N, E, G):
    diameter, center1, center2 = get_center(N, G)
    half = diameter // 2
    dep = [0 for _ in range(N)]
    sz = [0 for _ in range(N)]
    cnt = [0 for _ in range(N)]
    top = [0 for _ in range(N)]

    def dfs(u, par, dep_cur, top_cur):
        nonlocal G, half, dep, sz, cnt, top
        dep[u] = dep_cur
        top[u] = top_cur
        sz[u] = 1
        if dep[u] == half:
            cnt[u] = 1
        for v in G[u]:
            if v != par:
                dfs(v, u, dep_cur + 1, top_cur)
                cnt[u] += cnt[v]
                sz[u] += sz[v]

    ans_before = 0
    ans = [0 for _ in range(N-1)]

    if diameter == half * 2:
        occur_half = sum_sz = 0
        for r in G[center1]:
            dfs(r, center1, 1, r)
            if cnt[r] > 0:
                occur_half += 1
                sum_sz += sz[r]

        ans_before = sum(dep[i] + half for i in range(N))

        for i, (u, v) in enumerate(E):
            if dep[u] > dep[v]:
                u, v = v, u
            ans[i] = ans_before - (dep[u] + half) - sz[v]
            if occur_half == 2 and cnt[top[v]] > 0 and cnt[top[v]] == cnt[v]:
                ans[i] -= sum_sz - sz[top[v]]
    else:
        dfs(center1, center2, 0, center1)
        dfs(center2, center1, 0, center2)
        ans_before = sum(dep[i] + half + 1 for i in range(N))

        for i, (u, v) in enumerate(E):
            ans[i] = ans_before
            if (u, v) == (center1, center2) or (u, v) == (center2, center1):
                ans[i] -= half + N
            else:
                if dep[u] > dep[v]:
                    u, v = v, u
                ans[i] -= dep[u] + half + 1 + sz[v]
                if cnt[top[v]] == cnt[v]:
                    ans[i] -= N - sz[top[v]]

    return ans

N = int(input())
E = []
G = [[] for _ in range(N)]
for i in range(N-1):
    u, v = map(int, input().split())
    u -= 1; v -= 1
    E.append((u, v))
    G[u].append(v)
    G[v].append(u)
ans = solve(N, E, G)
for x in ans:
    print(x)
0