Submission #784844

#	Time	Username	Problem	Language	Result	Execution time	Memory
784844		cadmiumsky	Ancient Books (IOI17_books)	C++17	100 / 100	1848 ms	366700 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<vector<pii>> g;
  void init(int dim) { g.resize(dim, vector<pii>()); }
  int newnode() { g.emplace_back(); return sz(g) - 1; }
  void addedge(int x, int y, int z) {
    g[x].emplace_back(y, z);
  }
  
  namespace AINT {
    int aint[(nmax + nmax / 2) * 2];
    void init(int node = 1, int cl = 0, int cr = n - 1) {
      if(cl == cr) {
        aint[node] = cl;
        return;
      }
      int mid = cl + cr >> 1;
      init(2 * node, cl, mid);
      init(2 * node + 1, mid + 1, cr);
      aint[node] = newnode();
      addedge(aint[2 * node], aint[node], 0);
      addedge(aint[2 * node + 1], aint[node], 0);
      return;
    }
    void pushto(int val, int l, int r, int node = 1, int cl = 0, int cr = n - 1) {
      if(r < cl || cr < l) return;;
      if(l <= cl && cr <= r) {
        addedge(aint[node], val, 0);
        return;
      }
      int mid = cl + cr >> 1;
      pushto(val, l, r, 2 * node, cl, mid);
      pushto(val, l, r, 2 * node + 1, mid + 1, cr);
    }
  }
  
  vector<int> arriv, occ;
  vector<int> heap[nmax];
  vector<int> dijkstra(int s = -1) {
    arriv.resize(sz(g));
    occ.resize(sz(g));
    for(int i = 0; i <= n + 2; i++) heap[i].clear();
    //cerr << sz(arriv) << ' ' << sz(g) << '\n';
    fill(all(occ), 0);
    if(s != -1) {
      fill(all(arriv), inf);
      heap[0].emplace_back(s);
      arriv[s] = 0;
    }
    else {
      for(int i = 0; i < sz(g); i++)
        arriv[i] = min(arriv[i], n + 2),
        heap[arriv[i]].emplace_back(i);
    }
    for(int i = 0; i < n + 2; i++) {
      int c = i;
      for(int j = 0; j < sz(heap[i]); j++) {
        auto node = heap[i][j];
        if(occ[node]) continue;
        occ[node] = 1;
        for(auto [x, e] : g[node]) {
          if(arriv[x] > c + e) {
            arriv[x] = c + e;
            heap[arriv[x]].emplace_back(x);
          }
        }
      }
    }
    return arriv;
  }
}

long long minimum_walk(std::vector<signed> p, signed s) {
  n = sz(p);
  vector<int> col(n, 0);
  vector<int> rs(n + 2, 0), ls(n + 2, 0);
  int flag = 0;
  
  ll sum = 0;
  
  G::init(n);
  G::AINT::init();
  
  for(int i = 0; i < n; i++) {
    if(col[i] == 0 && p[i] != i) {
      flag++;
      int x = i, cnt = 0;
      int L = n;
      int R = -1;
      while(col[x] != flag) {
        col[x] = flag;
        L = min(x, L);
        R = max(x, R);
        sum += abs(x - p[x]);
        x = p[x];
        cnt++;
      }
      flag++;
      x = i;
      int u = G::newnode();
      G::AINT::pushto(u, L, R);
      while(col[x] != flag) {
        col[x] = flag;
        G::addedge(u, x, 0);
        x = p[x];
      }
    }
    if(i > 0)
      G::addedge(i - 1, i, 1),
      G::addedge(i, i - 1, 1);
  }
  
  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 < sz(G::g); i++) {
    G::arriv[i] = fl[i] + fr[i];
  }
  auto rez = G::dijkstra();
  
  return sum + (ll)rez[s] * 2;
}
#undef int

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

Compilation message (stderr)

books.cpp: In function 'void G::AINT::init(int, int, int)':
books.cpp:33:20: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   33 |       int mid = cl + cr >> 1;
      |                 ~~~^~~~
books.cpp: In function 'void G::AINT::pushto(int, int, int, int, int, int)':
books.cpp:47:20: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   47 |       int mid = cl + cr >> 1;
      |                 ~~~^~~~

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