結果

問題 No.1227 I hate ThREE
ユーザー WSKR
提出日時 2020-09-22 00:51:35
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 537 ms / 2,000 ms
コード長 3,462 bytes
コンパイル時間 251 ms
コンパイル使用メモリ 82,432 KB
実行使用メモリ 124,416 KB
最終ジャッジ日時 2024-06-25 00:17:41
合計ジャッジ時間 10,930 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge3
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ファイルパターン 結果
sample AC * 3
other AC * 33
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ソースコード

diff # 

#i hate three
from collections import deque

mod = 10**9 + 7


def main():
    N, C = map(int, input().split())
    G = [[] for i in range(N+1)]
    for i in range(N-1):
        a, b = map(int, input().split())
        G[a].append(b)
        G[b].append(a)

    visited = [False for i in range(N+1)]
    depth = [0 for i in range(N+1)]
    child_cnt = [1 for i in range(N+1)]

    que = deque([])

    def dfs(s_node):
        visited[s_node] = True
        for child in G[s_node]:
            if visited[child] == False:
                depth[child] = depth[s_node] + 1
                dfs(child)
        for child in G[s_node]:
            if depth[child] > depth[s_node]:
                child_cnt[s_node] += child_cnt[child]
        que.append(s_node)

    dfs(1)

    if C > 9*N:
        dp = [[0 for i in range(6*N-5)] for i in range(N+1)]
        while que:
            node = que.popleft()
            for i in range(3*N-3):
                has_child = False
                v = 1
                for child in G[node]:
                    if depth[child] > depth[node]:
                        tmp_u = 0
                        has_child = True
                        if i >= 3:
                            tmp_u += dp[child][i-3]

                        if i+3 <= 3*N-4:
                            tmp_u += dp[child][i+3]

                        elif i+3 > 3*N-4:
                            tmp_u += pow(2, child_cnt[child]-1, mod)

                        v *= tmp_u
                        v %= mod
                dp[node][i] = v
                if has_child == False:
                    dp[node][i] = 1

            for i in range(3*N-2, 6*N-5):
                has_child = False
                v = 1
                for child in G[node]:
                    if depth[child] > depth[node]:

                        tmp_u = 0
                        has_child = True
                        if i+3 <= 6*N-6:
                            tmp_u += dp[child][i+3]
                        if i-3 >= 3*N-2:
                            tmp_u += dp[child][i-3]
                        else:
                            tmp_u += pow(2, child_cnt[child]-1, mod)

                        v *= tmp_u
                        v %= mod
                dp[node][i] = v
                if has_child == False:
                    dp[node][i] = 1

        ans = sum(dp[1][i] for i in range(3*N-3)) + sum(dp[1][i]
                                                        for i in range(3*N-2, 6*N-5)) + (C-6*N + 6)*pow(2, N-1, mod)
        print(ans % mod)
        return

    elif C <= 9*N:
        dp = [[0 for i in range(C+1)] for j in range(N+1)]
        while que:
            node = que.popleft()
            for i in range(1, C+1):
                has_child = False
                v = 1
                for child in G[node]:
                    if depth[child] > depth[node]:
                        has_child = True
                        tmp_u = 0
                        if 1 <= i-3 <= C:
                            tmp_u += dp[child][i-3]
                        if 1 <= i+3 <= C:
                            tmp_u += dp[child][i+3]
                        v *= (tmp_u)
                        v %= mod
                dp[node][i] = v % mod
                if has_child == False:
                    dp[node][i] = 1

        ans = sum(dp[1][i] for i in range(1, C+1)) % mod
        print(ans)
        return


if __name__ == "__main__":
    main()
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