結果

問題 No.1103 Directed Length Sum
ユーザー 👑 hos.lyrichos.lyric
提出日時 2020-07-03 21:31:36
言語 D
(dmd 2.106.1)
結果
AC  
実行時間 1,045 ms / 3,000 ms
コード長 3,834 bytes
コンパイル時間 1,673 ms
コンパイル使用メモリ 155,940 KB
実行使用メモリ 168,492 KB
最終ジャッジ日時 2024-06-22 07:35:09
合計ジャッジ時間 14,302 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge2
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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 1 ms
6,812 KB
testcase_01 AC 2 ms
6,944 KB
testcase_02 AC 960 ms
168,492 KB
testcase_03 AC 607 ms
50,348 KB
testcase_04 AC 591 ms
30,084 KB
testcase_05 AC 1,045 ms
51,912 KB
testcase_06 AC 376 ms
22,820 KB
testcase_07 AC 79 ms
6,944 KB
testcase_08 AC 130 ms
10,176 KB
testcase_09 AC 49 ms
6,944 KB
testcase_10 AC 176 ms
13,744 KB
testcase_11 AC 652 ms
34,968 KB
testcase_12 AC 378 ms
23,648 KB
testcase_13 AC 199 ms
11,472 KB
testcase_14 AC 38 ms
6,940 KB
testcase_15 AC 303 ms
16,304 KB
testcase_16 AC 739 ms
36,428 KB
testcase_17 AC 768 ms
36,472 KB
testcase_18 AC 181 ms
13,380 KB
testcase_19 AC 668 ms
35,384 KB
testcase_20 AC 60 ms
6,940 KB
testcase_21 AC 114 ms
8,240 KB
testcase_22 AC 547 ms
29,372 KB
testcase_23 AC 317 ms
19,024 KB
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ソースコード

diff # 

import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }

struct ModInt(int M_) {
  import std.conv : to;
  alias M = M_;
  int x;
  this(ModInt a) { x = a.x; }
  this(long a) { x = cast(int)(a % M); if (x < 0) x += M; }
  ref ModInt opAssign(long a) { return (this = ModInt(a)); }
  ref ModInt opOpAssign(string op)(ModInt a) {
    static if (op == "+") { x += a.x; if (x >= M) x -= M; }
    else static if (op == "-") { x -= a.x; if (x < 0) x += M; }
    else static if (op == "*") { x = cast(int)((cast(long)(x) * a.x) % M); }
    else static if (op == "/") { this *= a.inv(); }
    else static assert(false);
    return this;
  }
  ref ModInt opOpAssign(string op)(long a) {
    static if (op == "^^") {
      if (a < 0) return (this = inv()^^(-a));
      ModInt t2 = this, te = ModInt(1);
      for (long e = a; e > 0; e >>= 1) {
        if (e & 1) te *= t2;
        t2 *= t2;
      }
      x = cast(int)(te.x);
      return this;
    } else return mixin("this " ~ op ~ "= ModInt(a)");
  }
  ModInt inv() const {
    int a = x, b = M, y = 1, z = 0, t;
    for (; ; ) {
      t = a / b; a -= t * b;
      if (a == 0) {
        assert(b == 1 || b == -1);
        return ModInt(b * z);
      }
      y -= t * z;
      t = b / a; b -= t * a;
      if (b == 0) {
        assert(a == 1 || a == -1);
        return ModInt(a * y);
      }
      z -= t * y;
    }
  }
  ModInt opUnary(string op: "-")() const { return ModInt(-x); }
  ModInt opBinary(string op, T)(T a) const {
    return mixin("ModInt(this) " ~ op ~ "= a");
  }
  ModInt opBinaryRight(string op)(long a) const {
    return mixin("ModInt(a) " ~ op ~ "= this");
  }
  bool opCast(T: bool)() const { return (x != 0); }
  string toString() const { return x.to!string; }
}

enum MO = 10^^9 + 7;
alias Mint = ModInt!MO;


int N;
int[] A, B;

int[][] graph;
Mint[] dp0, dp1;

void dfs(int u) {
  dp0[u] = 1;
  dp1[u] = 0;
  foreach (v; graph[u]) {
    dfs(v);
    dp0[u] += dp0[v];
    dp1[u] += dp0[v] + dp1[v];
  }
}

void main() {
  try {
    for (; ; ) {
      N = readInt();
      A = new int[N - 1];
      B = new int[N - 1];
      foreach (i; 0 .. N - 1) {
        A[i] = readInt() - 1;
        B[i] = readInt() - 1;
      }
      
      graph = new int[][N];
      auto indeg = new int[N];
      foreach (i; 0 .. N - 1) {
        graph[A[i]] ~= B[i];
        ++indeg[B[i]];
      }
      int rt = -1;
      foreach (u; 0 .. N) {
        if (indeg[u] == 0) {
          rt = u;
        }
      }
      assert(rt != -1);
      dp0 = new Mint[N];
      dp1 = new Mint[N];
      dfs(rt);
      debug {
        writeln("dp0 = ", dp0);
        writeln("dp1 = ", dp1);
      }
      const ans = dp1.sum;
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}
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