Submission #589977

#	Time	Username	Problem	Language	Result	Execution time	Memory
589977		Sam_a17	Shortcut (IOI16_shortcut)	C++14	23 / 100	2072 ms	4428 KiB

shortcut

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
// #include "shortcut_c.h"
#include <cstdio>
using namespace std;
#define ll long long

const int N = 2e3 + 10;
long long dist[N][N];
const ll inf = 1e16;
long long maxLeft[N], maxRight[N], kox[N];
long long maxLeftDiam[N], maxRightDiam[N];
multiset<pair<ll, long long>> adj[N];
int ni;

pair<long long, long long> djik(int node) {
  vector<bool> used(ni + 1);
  vector<long long> dist(ni + 1, inf);
  priority_queue<pair<ll, ll>, vector<pair<ll, ll>> , greater<pair<ll, ll>> > q;
  dist[node] = 0;
  q.push({0, node});
 
  while(!q.empty()) {
    auto u = q.top();
    q.pop();

    if(used[u.second]) {
      continue;
    }
    used[u.second] = true;

    for(auto i: adj[u.second]) {
      if(dist[i.first] > dist[u.second] + i.second) {
        dist[i.first] = dist[u.second] + i.second;
        q.push({dist[i.first], i.first});
      }
    }
  }

  pair<ll, ll> answ = {-1, -1};

  for(int i = 0; i < ni; i++) {
    if(dist[i] == inf) {
      assert(false);
    }

    if(dist[i] > answ.first) {
      answ = {dist[i], i};
    }
  }

  return answ;
}

void djik2(int node) {
  vector<bool> used(ni + 1);
  priority_queue<pair<ll, ll>, vector<pair<ll, ll>> , greater<pair<ll, ll>> > q;
  for(int i = 0; i < ni; i++) {
    dist[node][i] = inf;
  }
  dist[node][node] = 0;
  q.push({0, node});
 
  while(!q.empty()) {
    auto u = q.top();
    q.pop();

    if(used[u.second]) {
      continue;
    }
    used[u.second] = true;

    for(auto i: adj[u.second]) {
      if(dist[node][i.first] > dist[node][u.second] + i.second) {
        dist[node][i.first] = dist[node][u.second] + i.second;
        q.push({dist[node][i.first], i.first});
      }
    }
  }
}

void djik3(int node, vector<ll>& dist) {
  vector<bool> used(ni + 1);
  // vector<long long> dist(ni + 1, inf);
  priority_queue<pair<ll, ll>, vector<pair<ll, ll>> , greater<pair<ll, ll>> > q;
  dist[node] = 0;
  q.push({0, node});
 
  while(!q.empty()) {
    auto u = q.top();
    q.pop();

    if(used[u.second]) {
      continue;
    }
    used[u.second] = true;

    for(auto i: adj[u.second]) {
      if(dist[i.first] > dist[u.second] + i.second) {
        dist[i.first] = dist[u.second] + i.second;
        q.push({dist[i.first], i.first});
      }
    }
  }
}

long long find_shortcut(int n, std::vector<int> l, std::vector<int> d, int c) {
  maxLeft[0] = d[0];
  for(int i = 1; i < n; i++) {
    maxLeft[i] = max(maxLeft[i - 1] + (long long)l[i - 1], (long long)d[i]); 
  }

  maxRight[n - 1] = d[n - 1];
  for(int i = n - 2; i >= 0; i--) {
    maxRight[i] = max(maxRight[i + 1] + (long long)l[i], (long long)d[i]);
  }

  maxLeftDiam[0] = maxLeft[0];
  for(int i = 1; i < n; i++) {
    maxLeftDiam[i] = max(maxLeftDiam[i - 1], maxLeft[i - 1] + (long long)l[i - 1] + (long long)d[i]);
  }

  maxRightDiam[n - 1] = maxRight[n - 1];
  for(int i = n - 2; i >= 0; i--) {
    maxRightDiam[i] = max(maxRightDiam[i + 1], maxRight[i + 1] + (long long)l[i] + (long long)d[i]);
  }

  ni = n;

  if(d[0]) {
    kox[0] = ni;
    adj[0].insert({ni, d[0]});
    adj[ni++].insert({0, d[0]});
  }

  for(int i = 1; i < n; i++) {

    adj[i - 1].insert({i, l[i - 1]});
    adj[i].insert({i - 1, l[i - 1]});

    if(d[i]) {
      kox[i] = ni;
      adj[i].insert({ni, d[i]});
      adj[ni++].insert({i, d[i]});
    }
  }

  for(int i = 0; i < ni; i++) {
    djik2(i);
  }

  long long minDiametr = djik(djik(0).second).first;

  for(int i = 0; i < n; i++) {
    long long s = 0;
    for(int j = i + 1; j < n; j++) {
      s += l[j - 1];

      if(s <= c) {
        continue;
      }

      adj[i].insert({j, (long long)c});
      adj[j].insert({i, (long long)c});

      vector<long long> d1(ni + 1, inf), d2(ni + 1, inf);

      djik3(i, d1);
      djik3(j, d2);
      
      long long maxi = max({maxLeftDiam[i], maxRightDiam[j], maxLeft[i] + maxRight[j] + c});
      
      for(int k = i; k <= j; k++) {
        if(kox[k]) {
          for(int g = 0; g < ni; g++) {

            if(d1[kox[k]] + d1[g] < dist[kox[k]][g]) {
              maxi = max(maxi, d1[kox[k]] + d1[g]);
            } else {
              maxi = max(maxi, dist[kox[k]][g]);
            }

            if(d2[kox[k]] + d2[g] < dist[kox[k]][g]) {
              maxi = max(maxi, d2[kox[k]] + d2[g]);
            }else {
              maxi = max(maxi, dist[kox[k]][g]);
            }
          }
        } else {
          for(int g = 0; g < ni; g++) {
            if(d1[k] + d1[g] < dist[k][g]) {
              maxi = max(maxi, d1[k] + d1[g]);
            } else {
              maxi = max(maxi, dist[k][g]);
            }

            if(d2[k] + d2[g] < dist[k][g]) {
              maxi = max(maxi, d2[k] + d2[g]);
            } else {
              maxi = max(maxi, dist[k][g]);
            }
          }
        }
      }


      // cout << i << " " << j << endl;
      // cout << maxi << endl;

      minDiametr = min(maxi, minDiametr);

      adj[i].erase(adj[i].find(make_pair(j, (ll)c)));
      adj[j].erase(adj[j].find(make_pair(i, (ll)c)));
    }
  }

  return minDiametr;
}

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 0 / 8
• Subtask 4: 0 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3