제출 #415891

#제출 시각아이디문제언어결과실행 시간메모리
415891flashmt도로 폐쇄 (APIO21_roads)C++17
53 / 100
391 ms24368 KiB
#include <bits/stdc++.h>
using namespace std;
const long long oo = 1LL << 60;

int n, preDfs[100100], postDfs[100100], dfsTime, deg[100100], curDeg[100100], par[100100];
vector<pair<int, int>> a[100100];
long long f[100100];
long long g[100100]; // can keep parent edge
vector<int> nodes[100100];

void visit(int x, int k)
{
  f[x] = 0;
  vector<long long> gain;
  for (auto [y, w] : a[x])
    if (y != par[x])
    {
      visit(y, k);
      f[x] += f[y] + w;
      gain.push_back(g[y] - f[y] - w);
    }

  sort(gain.begin(), gain.end());
  g[x] = f[x];
  for (int i = 0; i < k && i < gain.size(); i++)
  {
    if (gain[i] >= 0)
      break;
    f[x] += gain[i];
    if (i < k - 1)
      g[x] += gain[i];
  }
  f[x] = min(f[x], g[x]);
}

void dfs(int x)
{
  preDfs[x] = ++dfsTime;
  for (auto [y, _] : a[x])
    if (y != par[x])
    {
      par[y] = x;
      dfs(y);
    }
  postDfs[x] = dfsTime;
}

int solve(int k, set<pair<int, int>> &nodes)
{
  for (auto [_, x] : nodes)
    curDeg[x] = deg[x];
  int res = 0;
  for (auto [_, x] : nodes)
    if (curDeg[x] > k)
    {
      res += curDeg[x] - k;
      if (par[x] >= 0)
        curDeg[par[x]]--;
    }
  return res;
}

vector<long long> minimum_closure_costs(int N, vector<int> U, vector<int> V, vector<int> W) {
  n = N;
  int isLine = 1, isWeighted = 0;
  for (int i = 0; i < n - 1; i++)
  {
    a[U[i]].push_back({V[i], W[i]});
    a[V[i]].push_back({U[i], W[i]});
    if (U[i] != i || V[i] != i + 1)
      isLine = 0;
    deg[U[i]]++;
    deg[V[i]]++;
    if (W[i] > 1)
      isWeighted = 1;
  }
  for (int i = 0; i < n; i++)
    nodes[deg[i]].push_back(i);

  vector<long long> ans(n);
  ans[0] = accumulate(W.begin(), W.end(), 0LL);

  dfsTime = 0;
  par[0] = -1;
  dfs(0);

  // 1
 if (a[0].size() == n - 1)
 {
   sort(W.begin(), W.end(), greater<int>());
   for (int i = n - 2; i >= 0; i--)
     ans[i] = ans[i + 1] + W[i];
   return ans;
 }

 // 2
 if (isLine)
 {
   vector<long long> f(n, oo);
   f[0] = 0;
   f[1] = W[0];
   for (int i = 2; i < n; i++)
     f[i] = min(f[i - 1], f[i - 2]) + W[i - 1];
   ans[1] = min(f[n - 1], f[n - 2]);
 }

  if (n <= 2000)
  {
    for (int i = 1; i < n - 1; i++)
    {
      visit(0, i);
      ans[i] = f[0];
    }
  }
  else if (!isWeighted)
  {
    set<pair<int, int>> s;
    for (int i = 0; i < n; i++)
      s.insert({-preDfs[i], i});
    for (int i = 1; i < n - 1; i++)
    {
      for (int x : nodes[i])
        s.erase({-preDfs[x], x});
      ans[i] = solve(i, s);
    }
  }

  return ans;
}

컴파일 시 표준 에러 (stderr) 메시지

roads.cpp: In function 'void visit(int, int)':
roads.cpp:25:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |   for (int i = 0; i < k && i < gain.size(); i++)
      |                            ~~^~~~~~~~~~~~~
roads.cpp: In function 'std::vector<long long int> minimum_closure_costs(int, std::vector<int>, std::vector<int>, std::vector<int>)':
roads.cpp:88:18: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   88 |  if (a[0].size() == n - 1)
      |      ~~~~~~~~~~~~^~~~~~~~
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