Submission #306811

#	Time	Username	Problem	Language	Result	Execution time	Memory
306811		quocnguyen1012	Swapping Cities (APIO20_swap)	C++14	100 / 100	664 ms	53488 KiB

swap

#ifndef LOCAL
#include "swap.h"
#endif // LOCAl
#include <bits/stdc++.h>

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define ar array

using namespace std;
typedef long long ll;
typedef pair<int, int> ii;

const int maxn = 2e5 + 5;

class DSU
{
public:
  class node
  {
  public:
    int pa, max_deg, cycle, updated;
    bool operator < (const node & other) const
    {
      return updated < other.updated;
    }
  };
  vector<node> nodes[maxn];
  vector<int> memb[maxn];
  int deg[maxn];
  void init(int n)
  {
    for(int i = 0; i < n; ++i){
      memb[i].clear();
      nodes[i].clear();
      memb[i].pb(i);
      nodes[i].pb({i, 0, 0, -1});
    }
  }
  int finds(int u)
  {
    return nodes[u].back().pa;
  }
  void add_edge(int u, int v, int i)
  {
    deg[u]++; deg[v]++;
    int new_deg = max(deg[u], deg[v]);
    u = finds(u); v = finds(v);
    if(u != v){
      if(memb[u].size() < memb[v].size()) swap(u, v);
      for(auto & x : memb[v]){
        node prv = nodes[x].back();
        prv.pa = u;
        prv.updated = i;
        nodes[x].pb(prv);
        memb[u].pb(x);
      }
      node prv = nodes[u].back();
      prv.max_deg = max(prv.max_deg, nodes[v].back().max_deg);
      prv.cycle |= nodes[v].back().cycle;
      prv.updated = i;
      nodes[u].pb(prv);
      memb[v].clear();
    }
    node prv = nodes[u].back();
    if(u == v)
      prv.cycle = true;
    prv.max_deg = max(prv.max_deg, new_deg);
    prv.updated = i;
    nodes[u].pb(prv);
  }
  node get_node(int u, int t)
  {
    return *--upper_bound(nodes[u].begin(), nodes[u].end(), (node){-1, -1, 0, t});
  }
}dsu;

vector<ar<int, 3>> edge;
int N, M;

bool isValid(int u, int v, int t)
{
  auto pu = dsu.get_node(u, t), pv = dsu.get_node(v, t);
  if(pu.pa != pv.pa) return false;
  auto val = dsu.get_node(pu.pa, t);
  return val.max_deg >= 3 || val.cycle;
}

void init(int _N, int _M,
		std::vector<int> U, std::vector<int> V, std::vector<int> W) {
  N = _N; M = _M;
  dsu.init(N);
  edge.resize(M);
  for(int i = 0; i < M; ++i){
    edge[i] = {W[i], U[i], V[i]};
  }
  sort(edge.begin(), edge.end());
  for(int i = 0; i < M; ++i){
    dsu.add_edge(edge[i][1], edge[i][2], i);
  }
}

int getMinimumFuelCapacity(int X, int Y) {
  int lo = 0, hi = M - 1;
  while(lo <= hi){
    int mid = (lo + hi) / 2;
    if(isValid(X, Y, mid)) hi = mid - 1;
    else lo = mid + 1;
  }
  if(lo == M) return -1;
  return edge[lo][0];
}

#ifdef LOCAL
signed main(void){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  #ifdef LOCAL
    freopen("A.INP", "r", stdin);
    freopen("A.OUT", "w", stdout);
  #endif // LOCAL
  int N, M; cin >> N >> M;
  vector<int> U(M), V(M), W(M);
  for(int i = 0; i < M; ++i){
    cin >> U[i];
  }
  for(int i = 0; i < M; ++i){
    cin >> V[i];
  }
  for(int i = 0; i < M; ++i){
    cin >> W[i];
  }
  init(N, M, U, V, W);
  int Q; cin >> Q;
  while(Q--){
    int x, y; cin >> x >> y;
    cout << getMinimumFuelCapacity(x, y) << '\n';
  }
}
#endif

• Subtask 1: 6 / 6
• Subtask 2: 7 / 7
• Subtask 3: 17 / 17
• Subtask 4: 20 / 20
• Subtask 5: 23 / 23
• Subtask 6: 27 / 27