Submission #584051

#	Time	Username	Problem	Language	Result	Execution time	Memory
584051		Sam_a17	Link (CEOI06_link)	C++14	100 / 100	386 ms	34076 KiB

link

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;

#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif

#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt __builtin_popcount

#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
#define ll long long

void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
void print(long double t) {cerr << t;}

template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T> void print(T v[],T n) {cerr << "["; for(int i = 0; i < n; i++) {cerr << v[i] << " ";} cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'

// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};

// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
  fastIO();

  if (str != "") {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
  }
}

// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 5e5 + 10, inf = 1e9;
int n, k, in[N], dist[N], answ;
vector<int> adj[N];
bool used[N];

int cycle(int node) {
  // dbg(node)
  int cur = node;
  vector<int> path;
  while(!used[cur]) {
    used[cur] = true;
    path.push_back(cur);
    cur = adj[cur][0];
  }

  // dbg(path)

  // dbg(sz(path))

  for(auto i: path) {
    used[i] = false;
  }

  {
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>> > q;

    for(auto i: path) {
      q.push({dist[i], i});
    }

    while(!q.empty()) {
      auto u = q.top();
      q.pop();
      if(used[u.second]) {
        continue;
      }
      used[u.second] = true;

      if(u.first >= k) {
        break;
      }

      for(auto i: adj[u.second]) {
        if(dist[i] > dist[u.second] + 1) {
          dist[i] = dist[u.second] + 1;
          q.push({dist[i], i});
        }
      }
    }
  }
  
  int m = sz(path);

  int mini = 0;
  for(int i = 0; i < m; i++) {
    if(dist[path[i]] == inf) {
      ++mini;
    }
  }

  if(!mini) {
    for(auto i: path) {
      used[i] = true;
    }
    return 0;
  }

  // dbg("done")

  int lst = -1;
  vector<int> ptr(m, 0);
  for(int i = 2 * m - 1; i >= 0; i--) {
    if(dist[path[i % m]] == inf) {
      lst = i % m;
      ptr[lst] = lst;
    } else if(lst != -1) {
      // assert(lst != -1);
      ptr[i % m] = lst;
    }
  }

  // dbg(ptr)

  for(int start = 0; start < min(k, m); start++) {
    int road = 0, pos = start, ansi = 0;
    // dbg(start)
    while(true) {
      if(ptr[pos] < pos) {
        road += ptr[pos] + m - pos;
      } else {
        road += ptr[pos] - pos;
      }
        pos = ptr[pos];
      
      if(road >= m) {
        break;
      }

      ansi++, road += k;
      pos += k, pos %= m;
    }

    // assert(false);
    mini = min(mini, ansi);
  }

  //
  for(auto i: path) {
    used[i] = true;
  }

  return mini;
}

void solve_() {
  cin >> n >> k;
  for(int i = 1; i <= n; i++) {
    int a, b; cin >> a >> b;
    adj[a].push_back(b); in[b]++;
  }

  for(int i = 2; i <= n; i++) {
    if(!in[i]) {
      adj[1].push_back(i);
      in[i]++;
      answ++;
    }
  }

  {
    for(int i = 1; i <= n; i++) {
      dist[i] = inf;
    }

    queue<pair<int, int>> q;
    q.push({1, 0});
    dist[1] = 0;
    used[1] = true;

    while(!q.empty()) {
      auto u = q.front();
      q.pop();

      // dbg(u)
      if(u.second > k) {
        dist[u.first] = 1;
        answ++;
      }

      for(auto i: adj[u.first]) {
        in[i]--;
        dist[i] = min(dist[i], dist[u.first] + 1);

        if(!in[i]) {
          used[i] = true;
          q.push({i, dist[i]}); 
        }
      }
    }
  }

  // for(int i = 1; i <= n; i++) {
    // dbg(dist[i])
  // }

  // dbg(answ)

  for(int i = 1; i <= n; i++) {
    if(!used[i]) {
      answ += cycle(i);
    }
  }

  printf("%d\n", answ);
}

int main () {
  setIO("");

  auto solve = [&](int test_case)-> void {
    while(test_case--) {
      solve_();
    }
  };

  int test_cases = 1;
  solve(test_cases);

  return 0;
}

Compilation message (stderr)

link.cpp: In function 'void setIO(std::string)':
link.cpp:65:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |     freopen((str + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
link.cpp:66:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   66 |     freopen((str + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100