Submission #784795

#	Time	Username	Problem	Language	Result	Execution time	Memory
784795		cadmiumsky	Ancient Books (IOI17_books)	C++17	12 / 100	14 ms	23788 KiB

books

#include <bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
using namespace std;

using ll = long long;
using ld = long double;

//#define int ll
#define sz(x) ((int)(x).size())

using pii = pair<int,int>;
using tii = tuple<int,int,int>;

const int nmax = 1e6 + 5, inf = 1e9 + 5;

int n;

namespace G {
  vector<pii> g[nmax];
  void addedge(int x, int y, int z) {
    g[x].emplace_back(y, z);
  }
  priority_queue<pii, vector<pii>, greater<pii>> heap;
  vector<int> arriv, occ;
  vector<int> dijkstra(int s = -1) {
    arriv.resize(n);
    occ.resize(n);
    fill(all(occ), 0);
    if(s != -1) {
      fill(all(arriv), inf);
      heap.emplace(0, s);
      arriv[s] = 0;
    }
    else {
      for(int i = 0; i < n; i++)
        heap.emplace(arriv[i], i);
    }
    while(!heap.empty()) {
      auto [c, node] = heap.top();
      heap.pop();
      if(occ[node]) continue;
      occ[node] = 1;
      for(auto [x, e] : g[node]) {
        if(arriv[x] > c + e) {
          arriv[x] = c + e;
          heap.emplace(arriv[x], x);
        }
      }
    }
    return arriv;
  }
}

long long minimum_walk(std::vector<int> p, int s) {
  n = sz(p);
  vector<int> col(n, 0);
  vector<int> rs(n + 2, 0), ls(n + 2, 0);
  int flag = 0;
  
  multiset<int> lhf;
  
  ll sum = 0;
  
  for(int i = 0; i < n; i++) {
    if(col[i] == 0) {
      flag++;
      int x = i, cnt = 0;
      set<int> vals;
      while(col[x] != flag) {
        col[x] = flag;
        sum += abs(x - p[x]);
        x = p[x];
        cnt++;
        vals.emplace(x);
      }
      int L = *vals.begin();
      int R = *vals.rbegin();
      flag++;
      x = i;
      while(col[x] != flag) {
        col[x] = flag;
        G::addedge(L, x, 0);
        G::addedge(R, x, 0);
        x = p[x];
      }
    }
    if(i > 0)
      G::addedge(i - 1, i, 2),
      G::addedge(i, i - 1, 2);
  }
  
  int sl = 0, sr = n - 1;
  while(p[sl] == sl && sl < s) sl++;
  while(p[sr] == sr && sr > s) sr--;
  
  auto fl = G::dijkstra(sl), fr = G::dijkstra(sr);
  for(int i = 0; i < n; i++) {
    G::arriv[i] = fl[i] + fr[i];
  }
  auto rez = G::dijkstra();

  
  
  return sum + rez[s];
}

/**
      Anul asta se da centroid.
-- Surse oficiale
*/

• Subtask 1: 12 / 12
• Subtask 2: 0 / 10
• Subtask 3: 0 / 28
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30