Submission #985688

#	Time	Username	Problem	Language	Result	Execution time	Memory
985688		yoav_s	Swapping Cities (APIO20_swap)	C++17	17 / 100	2050 ms	22024 KiB

swap

#include <bits/stdc++.h>
using namespace std;

typedef int ll;
typedef pair<ll,ll> p;
typedef pair<ll, p> tri;
typedef vector<ll> v;
typedef vector<v> vv;
typedef vector<p> vp;
typedef vector<tri> vtri;
typedef vector<vtri> vvtri;
typedef vector<vvtri> vvvtri;
typedef vector<vv> vvv;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;
typedef vector<p> vp;
typedef vector<vp> vvp;
typedef vector<vvp> vvvp;
typedef vector<vvvp> vvvvp;
#define double long double
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<vvd> vvvd;

const ll mod = 1e9 + 7;
const ll INF = 1e18;

#define f first
#define s second
#define pb push_back
#define eb emplace_back
#define loop(a) for (ll i = 0; i < a; i++)
#define setmin(a, b) a = min(a, b)
#define setmax(a, b) a = max(a, b)
#define all(v) v.begin(), v.end()

#include "swap.h"
ll res = -1;
vvp graph;
ll maxW = -INF;
ll N;

void init(int Nn, int M, std::vector<int> U, std::vector<int> V, std::vector<int> W) {
    N = Nn;
    graph = vvp(N);
    for (ll i = 0; i < M; i++)
    {
      graph[U[i]].eb(V[i], W[i]);
      graph[V[i]].eb(U[i], W[i]);
      maxW = max(maxW, (ll)W[i]);
    }
}

int getMinimumFuelCapacity(int X, int Y) {
  ll mini = 0, maxi = maxW + 1;
  while (mini < maxi)
  {
    ll mid = (mini + maxi) / 2;
    vv curGraph(N);
    for (ll i= 0 ; i < N; i++)
    {
      for (auto x : graph[i]) if (x.s <= mid) curGraph[i].pb(x.f);
    }
    v accessibleVertices;
    stack<ll> dfs;
    vb visited(N, false);
    dfs.push(X);
    while (!dfs.empty())
    {
      auto top = dfs.top();
      dfs.pop();
      if (visited[top]) continue;
      visited[top] = true;
      accessibleVertices.pb(top);
      for (ll x : curGraph[top]) dfs.push(x);
    }
    bool poss = false;
    if (visited[Y])
    {
      for (ll x : accessibleVertices) if (curGraph[x].size() >= 3) poss = true;
      ll edgeCount = 0;
      for (ll x : accessibleVertices) edgeCount += curGraph[x].size();
      edgeCount /= 2;
      if (edgeCount >= accessibleVertices.size()) poss = true;
    }
    if (poss)
    {
      maxi = mid;
    }
    else
    {
      mini = mid + 1;
    
    }
  }
  if (mini > maxW) return -1;
  return mini;
}
/*
int main() {
  int N, M;
  assert(2 == scanf("%d %d", &N, &M));
  
  std::vector<int> U(M), V(M), W(M);
  for (int i = 0; i < M; ++i) {
    assert(3 == scanf("%d %d %d", &U[i], &V[i], &W[i]));
  }

  int Q;
  assert(1 == scanf("%d", &Q));

  std::vector<int> X(Q), Y(Q);
  for (int i = 0; i < Q; ++i) {
    assert(2 == scanf("%d %d", &X[i], &Y[i]));
  }

  init(N, M, U, V, W);
  
  std::vector<int> minimum_fuel_capacities(Q);
  for (int i = 0; i < Q; ++i) {
    minimum_fuel_capacities[i] = getMinimumFuelCapacity(X[i], Y[i]);
  }

  for (int i = 0; i < Q; ++i) {
    printf("%d\n", minimum_fuel_capacities[i]);
  }
  
  return 0;
}
/**/

Compilation message (stderr)

swap.cpp:131:1: warning: "/*" within comment [-Wcomment]
  131 | /**/
      |  
swap.cpp:27:16: warning: overflow in conversion from 'double' to 'll' {aka 'int'} changes value from '1.0e+18' to '2147483647' [-Woverflow]
   27 | const ll INF = 1e18;
      |                ^~~~
swap.cpp: In function 'int getMinimumFuelCapacity(int, int)':
swap.cpp:85:21: warning: comparison of integer expressions of different signedness: 'll' {aka 'int'} and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |       if (edgeCount >= accessibleVertices.size()) poss = true;
      |           ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 7
• Subtask 3: 17 / 17
• Subtask 4: 0 / 20
• Subtask 5: 0 / 23
• Subtask 6: 0 / 27