Submission #2262112


Source Code Expand

/**
 * File    : E.cpp
 * Author  : Kazune Takahashi
 * Created : 2018-3-25 21:58:58
 * Powered by Visual Studio Code
 */

#include <iostream>
#include <iomanip>   // << fixed << setprecision(xxx)
#include <algorithm> // do { } while ( next_permutation(A, A+xxx) ) ;
#include <vector>
#include <string> // to_string(nnn) // substr(m, n) // stoi(nnn)
#include <complex>
#include <tuple>
#include <queue>
#include <stack>
#include <map> // if (M.find(key) != M.end()) { }
#include <set>
#include <random> // random_device rd; mt19937 mt(rd());
#include <cctype>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
using namespace std;

#define DEBUG 0 // change 0 -> 1 if we need debug.

typedef long long ll;

// const int dx[4] = {1, 0, -1, 0};
// const int dy[4] = {0, 1, 0, -1};

// const int C = 1e6+10;
// const ll M = 1000000007;

const int MAX_SIZE = 1000010;
const long long MOD = 1000000007;

long long inv[MAX_SIZE];
long long fact[MAX_SIZE];
long long factinv[MAX_SIZE];

const int UFSIZE = 100010;
int union_find[UFSIZE];

int root(int a) {
  if (a == union_find[a]) return a;
  return (union_find[a] = root(union_find[a]));
}

bool issame(int a, int b) {
  return root(a) == root(b);
}

void unite(int a, int b) {
  union_find[root(a)] = root(b);
}

bool isroot(int a) {
  return root(a) == a;
}

void init() {
  inv[1] = 1;
  for (int i=2; i<MAX_SIZE; i++) {
    inv[i] = ((MOD - inv[MOD%i]) * (MOD/i))%MOD;
  }
  fact[0] = factinv[0] = 1;
  for (int i=1; i<MAX_SIZE; i++) {
    fact[i] = (i * fact[i-1])%MOD;
    factinv[i] = (inv[i] * factinv[i-1])%MOD;
  }
  for (auto i=0; i<UFSIZE; i++) {
    union_find[i] = i;
  }
}

long long C(int n, int k) {
  if (n >=0 && k >= 0 && n-k >= 0) {
    return ((fact[n] * factinv[k])%MOD * factinv[n-k])%MOD;
  }
  return 0;
}

long long power(long long x, long long n) {
  if (n == 0) {
    return 1;
  } else if (n%2 == 1) {
    return (x * power(x, n-1)) % MOD;
  } else {
    long long half = power(x, n/2);
    return (half * half) % MOD;
  }
}

long long gcm(long long a, long long b) {
  if (a < b) {
    return gcm(b, a);
  }
  if (b == 0) return a;
  return gcm(b, a%b);
}

typedef tuple<ll, int, int> edge;
typedef tuple<ll, int> path;

int N, M;
ll X;
vector<edge> V;
vector<path> T[1010];
vector<edge> W;

path parent[10][1010];
int depth[1010];

void dfs(int v, int p, ll cost, int d)
{
  parent[0][v] = path(cost, p);
  depth[v] = d;
  for (auto x : T[v])
  {
    if (get<1>(x) != p)
    {
      dfs(get<1>(x), v, get<0>(x), d + 1);
    }
  }
}

void init2()
{
  dfs(0, -1, 0, 0);
  for (auto k = 0; k+1 < 10; k++)
  {
    for (auto v = 0; v < N; v++)
    {
      if (get<1>(parent[k][v]) < 0)
      {
        parent[k + 1][v] = path(0, -1);
      }
      else
      {
        ll cost = get<0>(parent[k][v]);
        int u = get<1>(parent[k][v]);
        int new_u = get<1>(parent[k][u]);
        ll new_cost = max(cost, get<0>(parent[k][u]));
        parent[k + 1][v] = path(new_cost, new_u);
#if DEBUG == 1
        cerr << "parent[" << k + 1 << "][" << v << "] = (" << new_cost << ", " << new_u << ")" << endl;
#endif
      }
    }
  }
}

ll lca(int u, int v)
{
  if (depth[u] > depth[v])
    swap(u, v);
  ll ans = 0;
#if DEBUG == 1
  cerr << "depth[" << u << "] = " << depth[u]
       << ", depth[" << v << "] = " << depth[v] << endl;
#endif
  for (auto k = 0; k < 10; k++)
  {
    if ((depth[v] - depth[u]) >> k & 1)
    {
      ans = max(ans, get<0>(parent[k][v]));
      v = get<1>(parent[k][v]);
    }
  }
  if (u == v)
    return ans;
  for (auto k = 9; k >= 0; k--)
  {
    if (get<1>(parent[k][u]) != get<1>(parent[k][v]))
    {
      u = get<1>(parent[k][u]);
      v = get<1>(parent[k][v]);
      ans = max(ans, get<0>(parent[k][u]));
      ans = max(ans, get<0>(parent[k][v]));
    }
  }
  ans = max(ans, get<0>(parent[0][v]));
  ans = max(ans, get<0>(parent[0][u]));
  return ans;
}

int main()
{
  init();
  cin >> N >> M;
  cin >> X;
  for (auto i = 0; i < M; i++)
  {
    int u, v;
    ll w;
    cin >> u >> v >> w;
    u--;
    v--;
    V.push_back(edge(w, u, v));
  }
  sort(V.begin(), V.end());
  ll Y = 0;
  for (auto e : V)
  {
    ll cost = get<0>(e);
    int u = get<1>(e);
    int v = get<2>(e);
    if (!issame(u, v))
    {
      unite(u, v);
      T[u].push_back(path(cost, v));
      T[v].push_back(path(cost, u));
      Y += cost;
    }
    else
    {
      W.push_back(e);
    }
  }
#if DEBUG == 1
  cerr << "X = " << X << ", Y = " << Y << endl;
#endif
  if (X < Y)
  {
    cout << 0 << endl;
    return 0;
  }
  ll ans = 0;
  ll K = N - 1;
  ll L = W.size();
  if (X == Y)
  {
    ans = (((power(2, K) + MOD - 2) % MOD) * power(2, L)) % MOD;
  }
#if DEBUG == 1
  cerr << "L = " << L << ", ans = " << ans << endl;
#endif
  init2();
  ll L1 = 0;
  ll L2 = 0;
  for (auto e : W)
  {
    ll cost = get<0>(e);
    int u = get<1>(e);
    int v = get<2>(e);
    ll temp = cost - lca(u, v);
    if (temp < X - Y)
      L2++;
    else if (temp == X - Y)
      L1++;
  }
#if DEBUG == 1
  cerr << "L1 = " << L1 << ", L2 = " << L2 << endl;
#endif
  ans += (2 * (power(2, L - L2) + MOD - power(2, L - L2 - L1))) % MOD;
  ans %= MOD;
  cout << ans << endl;
}

Submission Info

Submission Time
Task E - Bichrome Spanning Tree
User kazunetakahashi
Language C++14 (GCC 5.4.1)
Score 0
Code Size 5424 Byte
Status WA
Exec Time 45 ms
Memory 24448 KB

Judge Result

Set Name Sample All
Score / Max Score 0 / 0 0 / 900
Status
AC × 4
AC × 28
WA × 24
Set Name Test Cases
Sample sample-01.txt, sample-02.txt, sample-03.txt, sample-04.txt
All 01.txt, 02.txt, 03.txt, 04.txt, 05.txt, 06.txt, 07.txt, 08.txt, 09.txt, 10.txt, 11.txt, 12.txt, 13.txt, 14.txt, 15.txt, 16.txt, 17.txt, 18.txt, 19.txt, 20.txt, 21.txt, 22.txt, 23.txt, 24.txt, 25.txt, 26.txt, 27.txt, 28.txt, 29.txt, 30.txt, 31.txt, 32.txt, 33.txt, 34.txt, 35.txt, 36.txt, 37.txt, 38.txt, 39.txt, 40.txt, 41.txt, 42.txt, 43.txt, 44.txt, 45.txt, 46.txt, 47.txt, 48.txt, sample-01.txt, sample-02.txt, sample-03.txt, sample-04.txt
Case Name Status Exec Time Memory
01.txt WA 40 ms 24320 KB
02.txt WA 40 ms 24320 KB
03.txt AC 40 ms 24320 KB
04.txt WA 40 ms 24448 KB
05.txt WA 40 ms 24448 KB
06.txt WA 40 ms 24320 KB
07.txt WA 40 ms 24448 KB
08.txt AC 40 ms 24320 KB
09.txt WA 40 ms 24448 KB
10.txt AC 40 ms 24448 KB
11.txt AC 40 ms 24320 KB
12.txt AC 39 ms 24320 KB
13.txt AC 39 ms 24320 KB
14.txt AC 39 ms 24320 KB
15.txt WA 40 ms 24320 KB
16.txt AC 40 ms 24320 KB
17.txt WA 40 ms 24320 KB
18.txt AC 41 ms 24192 KB
19.txt WA 40 ms 24448 KB
20.txt AC 40 ms 24192 KB
21.txt WA 41 ms 24320 KB
22.txt AC 41 ms 24448 KB
23.txt AC 41 ms 24448 KB
24.txt WA 40 ms 24320 KB
25.txt AC 39 ms 24320 KB
26.txt WA 40 ms 24320 KB
27.txt WA 40 ms 24320 KB
28.txt WA 45 ms 24320 KB
29.txt WA 41 ms 24448 KB
30.txt WA 40 ms 24320 KB
31.txt AC 41 ms 24448 KB
32.txt WA 40 ms 24320 KB
33.txt WA 41 ms 24320 KB
34.txt AC 40 ms 24320 KB
35.txt WA 40 ms 24320 KB
36.txt WA 40 ms 24320 KB
37.txt WA 40 ms 24320 KB
38.txt AC 40 ms 24320 KB
39.txt AC 40 ms 24320 KB
40.txt AC 40 ms 24448 KB
41.txt AC 40 ms 24320 KB
42.txt AC 39 ms 24320 KB
43.txt AC 39 ms 24320 KB
44.txt AC 40 ms 24192 KB
45.txt WA 40 ms 24320 KB
46.txt WA 40 ms 24320 KB
47.txt AC 39 ms 24320 KB
48.txt AC 39 ms 24320 KB
sample-01.txt AC 38 ms 24192 KB
sample-02.txt AC 38 ms 24192 KB
sample-03.txt AC 38 ms 24064 KB
sample-04.txt AC 38 ms 24192 KB