結果

問題 No.1976 Cut then Connect
ユーザー tamatotamato
提出日時 2022-06-10 22:48:21
言語 PyPy3
(7.3.15)
結果
WA  
実行時間 -
コード長 6,106 bytes
コンパイル時間 160 ms
コンパイル使用メモリ 82,920 KB
実行使用メモリ 142,764 KB
最終ジャッジ日時 2024-09-21 06:41:34
合計ジャッジ時間 7,893 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge3
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 44 ms
54,656 KB
testcase_01 AC 44 ms
55,040 KB
testcase_02 WA -
testcase_03 WA -
testcase_04 WA -
testcase_05 WA -
testcase_06 WA -
testcase_07 AC 265 ms
98,560 KB
testcase_08 AC 476 ms
135,456 KB
testcase_09 WA -
testcase_10 WA -
testcase_11 WA -
testcase_12 WA -
testcase_13 AC 355 ms
118,116 KB
testcase_14 WA -
testcase_15 AC 318 ms
110,008 KB
testcase_16 WA -
testcase_17 WA -
testcase_18 WA -
testcase_19 WA -
testcase_20 WA -
testcase_21 WA -
testcase_22 AC 45 ms
55,040 KB
testcase_23 WA -
testcase_24 WA -
testcase_25 AC 43 ms
54,912 KB
testcase_26 AC 44 ms
54,784 KB
testcase_27 WA -
testcase_28 AC 44 ms
54,656 KB
testcase_29 AC 44 ms
54,784 KB
testcase_30 WA -
testcase_31 WA -
testcase_32 WA -
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 # 

mod = 998244353


def main():
    import sys
    from collections import deque
    input = sys.stdin.readline

    N = int(input())
    adj = [[] for _ in range(N + 1)]
    for _ in range(N - 1):
        a, b = map(int, input().split())
        adj[a].append(b)
        adj[b].append(a)

    que = deque()
    que.append(1)
    seen = [-1] * (N+1)
    seen[1] = 0
    par = [0] * (N+1)
    child = [[] for _ in range(N+1)]
    seq = []
    while que:
        v = que.popleft()
        seq.append(v)
        for u in adj[v]:
            if seen[u] == -1:
                seen[u] = seen[v] + 1
                par[u] = v
                child[v].append(u)
                que.append(u)
    seq.reverse()

    v0 = seq[0]
    que = deque()
    que.append(v0)
    seen = [-1] * (N+1)
    seen[v0] = 0
    par = [0] * (N+1)
    child = [[] for _ in range(N+1)]
    seq = []
    while que:
        v = que.popleft()
        seq.append(v)
        for u in adj[v]:
            if seen[u] == -1:
                seen[u] = seen[v] + 1
                par[u] = v
                child[v].append(u)
                que.append(u)
    seq.reverse()

    v1 = seq[0]
    D = seen[v1]
    if D & 1:
        v = v1
        for _ in range(D // 2):
            v = par[v]
        vl = v
        vr = par[v]
        vl_ori = vl
        vr_ori = vr

        que = deque()
        que.append(vl)
        seen = [-1] * (N+1)
        seen[vl] = 0
        par = [0] * (N+1)
        child = [[] for _ in range(N+1)]
        seq = []
        while que:
            v = que.popleft()
            seq.append(v)
            for u in adj[v]:
                if u == vr_ori:
                    continue
                if seen[u] == -1:
                    seen[u] = seen[v] + 1
                    par[u] = v
                    child[v].append(u)
                    que.append(u)
        seq.reverse()
        vl = seq[0]
        que = deque()
        que.append(vl)
        seen = [-1] * (N + 1)
        seen[vl] = 0
        par = [0] * (N + 1)
        child = [[] for _ in range(N + 1)]
        seq = []
        while que:
            v = que.popleft()
            seq.append(v)
            for u in adj[v]:
                if seen[u] == -1:
                    if u == vr_ori:
                        continue
                    seen[u] = seen[v] + 1
                    par[u] = v
                    child[v].append(u)
                    que.append(u)
        seq.reverse()
        dl = seen[seq[0]]

        que = deque()
        que.append(vr)
        seen = [-1] * (N + 1)
        seen[vr] = 0
        par = [0] * (N + 1)
        child = [[] for _ in range(N + 1)]
        seq = []
        while que:
            v = que.popleft()
            seq.append(v)
            for u in adj[v]:
                if seen[u] == -1:
                    if u == vl_ori:
                        continue
                    seen[u] = seen[v] + 1
                    par[u] = v
                    child[v].append(u)
                    que.append(u)
        seq.reverse()
        vr = seq[0]
        que = deque()
        que.append(vr)
        seen = [-1] * (N + 1)
        seen[vr] = 0
        par = [0] * (N + 1)
        child = [[] for _ in range(N + 1)]
        seq = []
        while que:
            v = que.popleft()
            seq.append(v)
            for u in adj[v]:
                if seen[u] == -1:
                    if u == vl_ori:
                        continue
                    seen[u] = seen[v] + 1
                    par[u] = v
                    child[v].append(u)
                    que.append(u)
        seq.reverse()
        dr = seen[seq[0]]

        print((dl + 1) // 2 + (dr + 1) // 2 + 1)
    else:
        ans = N * 2
        v = v1
        for _ in range(D // 2):
            v = par[v]
        v0 = v
        que = deque()
        que.append(v0)
        seen = [-1] * (N+1)
        seen[v0] = 0
        par = [0] * (N+1)
        child = [[] for _ in range(N+1)]
        seq = []
        while que:
            v = que.popleft()
            seq.append(v)
            for u in adj[v]:
                if seen[u] == -1:
                    seen[u] = seen[v] + 1
                    par[u] = v
                    child[v].append(u)
                    que.append(u)
        seq.reverse()

        subtree_len = [(0, 0)]
        for c in child[v0]:
            que = deque()
            seq = []
            que.append(c)
            while que:
                v = que.popleft()
                for vv in child[v]:
                    que.append(vv)
                seq.append(v)
            subtree_len.append((seen[seq[-1]], c))
        subtree_len.sort(key=lambda x: x[0], reverse=True)

        for c in child[v0]:
            cc = c
            que = deque()
            que.append(cc)
            seen = {}
            seen[cc] = 0
            seq = []
            while que:
                v = que.popleft()
                seq.append(v)
                for u in adj[v]:
                    if u == v0:
                        continue
                    if u not in seen:
                        seen[u] = seen[v] + 1
                        que.append(u)
            seq.reverse()
            cc = seq[0]
            que = deque()
            que.append(cc)
            seen = {}
            seen[cc] = 0
            seq = []
            while que:
                v = que.popleft()
                seq.append(v)
                for u in adj[v]:
                    if u == v0:
                        continue
                    if u not in seen:
                        seen[u] = seen[v] + 1
                        que.append(u)
            seq.reverse()
            dc = seen[seq[0]]

            if c == subtree_len[0][1]:
                dc2 = subtree_len[1][1] + subtree_len[2][1]

            elif c == subtree_len[1][1]:
                dc2 = subtree_len[0][1] + subtree_len[2][1]
            else:
                dc2 = subtree_len[0][1] + subtree_len[1][1]
            ans = min(ans, (dc + 1) // 2 + (dc2 + 1) // 2 + 1)
        print(ans)


if __name__ == '__main__':
    main()
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