結果

問題 No.827 総神童数
ユーザー kusomushikusomushi
提出日時 2019-07-08 20:43:32
言語 Java21
(openjdk 21)
結果
AC  
実行時間 785 ms / 2,000 ms
コード長 7,150 bytes
コンパイル時間 2,647 ms
コンパイル使用メモリ 79,476 KB
実行使用メモリ 71,260 KB
最終ジャッジ日時 2024-10-09 12:49:17
合計ジャッジ時間 20,548 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge1
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 56 ms
50,600 KB
testcase_01 AC 55 ms
50,612 KB
testcase_02 AC 56 ms
50,680 KB
testcase_03 AC 56 ms
50,576 KB
testcase_04 AC 56 ms
50,680 KB
testcase_05 AC 57 ms
50,588 KB
testcase_06 AC 56 ms
50,628 KB
testcase_07 AC 55 ms
50,284 KB
testcase_08 AC 56 ms
50,396 KB
testcase_09 AC 678 ms
69,600 KB
testcase_10 AC 400 ms
61,724 KB
testcase_11 AC 126 ms
52,664 KB
testcase_12 AC 244 ms
55,960 KB
testcase_13 AC 654 ms
67,208 KB
testcase_14 AC 158 ms
54,856 KB
testcase_15 AC 383 ms
61,840 KB
testcase_16 AC 683 ms
68,484 KB
testcase_17 AC 778 ms
70,904 KB
testcase_18 AC 416 ms
60,108 KB
testcase_19 AC 719 ms
69,088 KB
testcase_20 AC 617 ms
68,844 KB
testcase_21 AC 479 ms
62,440 KB
testcase_22 AC 664 ms
69,832 KB
testcase_23 AC 103 ms
51,900 KB
testcase_24 AC 683 ms
69,836 KB
testcase_25 AC 577 ms
65,744 KB
testcase_26 AC 736 ms
70,052 KB
testcase_27 AC 526 ms
66,476 KB
testcase_28 AC 523 ms
66,844 KB
testcase_29 AC 458 ms
62,568 KB
testcase_30 AC 245 ms
56,004 KB
testcase_31 AC 395 ms
61,204 KB
testcase_32 AC 396 ms
60,084 KB
testcase_33 AC 785 ms
71,260 KB
testcase_34 AC 737 ms
70,344 KB
testcase_35 AC 378 ms
59,068 KB
testcase_36 AC 484 ms
64,092 KB
testcase_37 AC 585 ms
67,116 KB
testcase_38 AC 767 ms
71,184 KB
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ソースコード

diff # 

import java.io.*;
import java.util.Arrays;
import java.util.StringJoiner;
import java.util.StringTokenizer;

public class Main {

    static int N;
    static int[] A, B;

    public static void main(String[] args) {
        FastScanner sc = new FastScanner(System.in);
        N = sc.nextInt();
        A = new int[N-1];
        B = new int[N-1];
        for (int i = 0; i < N - 1; i++) {
            A[i] = sc.nextInt()-1;
            B[i] = sc.nextInt()-1;
        }

        System.out.println(solve());
    }
    
    static int solve() {
        int[][] G = adjB(N, A, B);
        int[] dist = new int[N];
        for (Node node : order(N, G, 0, true)) {
            for (int b : G[node.a]) {
                if( b == node.parent ) continue;
                dist[b] = dist[node.a] + 1;
            }
        }

        int nFact = 1;
        for (int i = 2; i <= N; i++) {
            nFact = mul(i, nFact);
        }

        int ans = 0;
        for (int i = 0; i < N; i++) {
            int d = dist[i];
            // N! / (d+1)
            ans += div(nFact, d+1);
            ans %= MOD;
        }
        return ans;
    }

    static int MOD = 1_000_000_007;

    static int pow(int base, long exp) {
        if( exp == 0 ) return 1;

        int ans = 1;
        base %= MOD;
        while( exp > 0 ) {
            if( (exp & 1) == 1 ) {
                ans = mul(ans, base);
            }

            base = mul(base, base);
            exp = exp >> 1;
        }
        return ans;
    }

    static int sub(int a, int b) {
        int c = a - b;
        if( c < 0 ) c += MOD;
        return c;
    }

    static int div(int a, int b) {
        return mul(a, pow(b, MOD-2));
    }

    static int add(int a, int b) {
        int c = a + b;
        if( c >= MOD ) c %= MOD;
        return c;
    }

    static int mul(int a, int b) {
        long c = (long)a * b;
        if( c >= MOD ) c %= MOD;
        return (int)c;
    }
    
    static class Node {
        int parent, a;

        public Node(int parent, int a) {
            this.parent = parent;
            this.a = a;
        }
    }

    static Node[] order(int N, int[][] G, int root, boolean fromRoot) {
        Node[] q = new Node[N];
        int u = 0, v = 0;
        Node[] ret = new Node[N];
        int idx = fromRoot ? 0 : N-1;
        int d = fromRoot ? 1 : -1;
        q[v++] = new Node(-1, root);
        while( u != v ) {
            Node n = q[u++];
            ret[idx] = n;
            idx += d;
            for (int b : G[n.a]) {
                if( b == n.parent ) continue;

                q[v++] = new Node(n.a, b);
            }
        }
        return ret;
    }

    static int[][] adjB(int n, int[] from, int[] to) {
        int[][] adj = new int[n][];
        int[] cnt = new int[n];
        for (int f : from) {
            cnt[f]++;
        }
        for (int t : to) {
            cnt[t]++;
        }
        for (int i = 0; i < n; i++) {
            adj[i] = new int[cnt[i]];
        }
        for (int i = 0; i < from.length; i++) {
            adj[from[i]][--cnt[from[i]]] = to[i];
            adj[to[i]][--cnt[to[i]]] = from[i];
        }
        return adj;
    }

    @SuppressWarnings("unused")
    static class FastScanner {
        private BufferedReader reader;
        private StringTokenizer tokenizer;

        FastScanner(InputStream in) {
            reader = new BufferedReader(new InputStreamReader(in));
            tokenizer = null;
        }

        String next() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        String nextLine() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    return reader.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken("\n");
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] nextIntArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt();
            return a;
        }

        int[] nextIntArray(int n, int delta) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = nextInt() + delta;
            return a;
        }

        long[] nextLongArray(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++) a[i] = nextLong();
            return a;
        }
    }

    static void writeLines(int[] as) {
        PrintWriter pw = new PrintWriter(System.out);
        for (int a : as) pw.println(a);
        pw.flush();
    }

    static void writeLines(long[] as) {
        PrintWriter pw = new PrintWriter(System.out);
        for (long a : as) pw.println(a);
        pw.flush();
    }

    static void writeSingleLine(int[] as) {
        PrintWriter pw = new PrintWriter(System.out);
        for (int i = 0; i < as.length; i++) {
            if (i != 0) pw.print(" ");
            pw.print(as[i]);
        }
        pw.println();
        pw.flush();
    }

    static int max(int... as) {
        int max = Integer.MIN_VALUE;
        for (int a : as) max = Math.max(a, max);
        return max;
    }

    static int min(int... as) {
        int min = Integer.MAX_VALUE;
        for (int a : as) min = Math.min(a, min);
        return min;
    }

    static void debug(Object... args) {
        StringJoiner j = new StringJoiner(" ");
        for (Object arg : args) {
            if (arg == null) j.add("null");
            else if (arg instanceof int[]) j.add(Arrays.toString((int[]) arg));
            else if (arg instanceof long[]) j.add(Arrays.toString((long[]) arg));
            else if (arg instanceof double[]) j.add(Arrays.toString((double[]) arg));
            else if (arg instanceof Object[]) j.add(Arrays.toString((Object[]) arg));
            else j.add(arg.toString());
        }
        System.err.println(j.toString());
    }

    static void printSingleLine(int[] array) {
        PrintWriter pw = new PrintWriter(System.out);
        for (int i = 0; i < array.length; i++) {
            if (i != 0) pw.print(" ");
            pw.print(array[i]);
        }
        pw.println();
        pw.flush();
    }

    static int lowerBound(int[] array, int value) {
        int lo = 0, hi = array.length, mid;
        while (lo < hi) {
            mid = (hi + lo) / 2;
            if (array[mid] < value) lo = mid + 1;
            else hi = mid;
        }
        return lo;
    }

    static int upperBound(int[] array, int value) {
        int lo = 0, hi = array.length, mid;
        while (lo < hi) {
            mid = (hi + lo) / 2;
            if (array[mid] <= value) lo = mid + 1;
            else hi = mid;
        }
        return lo;
    }
}
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