結果

問題 No.827 総神童数
コンテスト
ユーザー akakimidori
提出日時 2019-06-06 18:50:02
言語 C
(gcc 13.3.0)
結果
AC  
実行時間 52 ms / 2,000 ms
コード長 2,365 bytes
コンパイル時間 549 ms
コンパイル使用メモリ 31,360 KB
実行使用メモリ 7,208 KB
最終ジャッジ日時 2024-10-01 08:46:03
合計ジャッジ時間 3,933 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
（要ログイン）
ファイルパターン 結果
sample AC * 3
other AC * 36
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 # 

#include<stdio.h>
#include<stdlib.h>
#include<stdint.h>
#include<inttypes.h>

typedef int32_t i32;
typedef int64_t i64;

typedef struct directed_edge {
  int32_t vertex;
  int32_t next;
} graph_edge;

typedef struct directedGraph {
  graph_edge *edge;
  int32_t *start;
  int32_t pointer;
  int32_t vertex_num;
  int32_t edge_max_size;
} graph;

graph* new_graph (const int vertex_num) {
  graph *g = (graph *) calloc (1, sizeof (graph));
  g->edge = (graph_edge *) calloc (1, sizeof (graph_edge));
  g->start = (int32_t *) calloc (vertex_num, sizeof (int32_t));
  g->pointer = 0;
  g->vertex_num = vertex_num;
  g->edge_max_size = 1;
  for (int32_t i = 0; i < vertex_num; ++i) {
    g->start[i] = -1;
  }
  return g;
}

void add_edge (graph *g, int32_t from, int32_t to) {
  if (g->pointer == g->edge_max_size) {
    g->edge_max_size *= 2;
    g->edge = (graph_edge *) realloc (g->edge, sizeof (graph_edge) * g->edge_max_size);
  }
  g->edge[g->pointer] = (graph_edge) {to, g->start[from]};
  g->start[from] = g->pointer++;
}

void BFS_graph (graph *g, int32_t src, i32 *d) {
  int32_t *q = (int32_t *) calloc (g->vertex_num, sizeof (int32_t));
  uint8_t *used = (uint8_t *) calloc (g->vertex_num, sizeof (uint8_t));
  int32_t front = 0;
  int32_t last = 0;
  used[src] = 1;
  q[last++] = src;
  while (front < last) {
    const int32_t v = q[front++];
    for (int32_t p = g->start[v]; p != -1; p = g->edge[p].next) {
      const int32_t u = g->edge[p].vertex;
      if (!used[u]) {
        used[u] = 1;
        q[last++] = u;
        d[u] = d[v] + 1;
      }
    }
  }
  free(q);
  free(used);
}

void run (void) {
  i32 n;
  scanf ("%" SCNi32, &n);
  graph *g = new_graph (n);
  for (i32 i = 1; i < n; ++i) {
    i32 a, b;
    scanf ("%" SCNi32 "%" SCNi32, &a, &b);
    a--; b--;
    add_edge (g, a, b);
    add_edge (g, b, a);
  }
  i32 *d = (i32 *) calloc (n, sizeof (i32));
  BFS_graph (g, 0, d);
  const i32 mod = 1000000007;
  i32 *inverse = (i32 *) calloc (n + 1, sizeof (i32));
  inverse[1] = 1;
  for (i32 i = 2; i <= n; ++i) {
    inverse[i] = (i64) (mod - mod / i) * inverse[mod % i] % mod;
  }
  i64 ans = 0;;
  for (i32 i = 0; i < n; ++i) {
    i32 x = d[i] + 1;
    ans += inverse[x];
  }
  ans %= mod;
  for (i32 i = 1; i <= n; ++i) {
    ans = (i64) ans * i % mod;
  }
  printf ("%" PRIi64 "\n", ans);
}

int main (void) {
  run();
  return 0;
}
0