Submission #891442

#	Time	Username	Problem	Language	Result	Execution time	Memory
891442		Zero_OP	Swapping Cities (APIO20_swap)	C++14	100 / 100	275 ms	64396 KiB

swap

#include<bits/stdc++.h>

using namespace std;

#define range(v) begin(v), end(v)
#define compact(v) v.erase(unique(range(v)), end(v))

template<class T> bool minimize(T& a, T b){
  if(a > b) return a = b, true;
  return false;
}

template<class T> bool maximize(T& a, T b){
  if(a < b) return a = b, true;
  return false;
}

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

const int N = 3e5 + 5;

struct edge{
  int u, v, w;
  bool operator < (const edge& o){
    return w < o.w;
  }
};

int n, m, q, nNodes, par[N], h[N], lift[20][N], weight[N], deg[N], lab[N];
bool good[N];
vector<int> adj[N];
vector<edge> edges;

int root(int u){
  return par[u] == u ? u : (par[u] = root(par[u]));
}

void addEdge(int u, int v, int w, int maxDeg){
  u = root(u), v = root(v);
  par[u] = nNodes;
  par[v] = nNodes;
  weight[nNodes] = w;
  good[nNodes] = good[u] || good[v];
  adj[nNodes].push_back(u);
  if(u == v) good[nNodes] = true;
  else{
    adj[nNodes].push_back(v);
    if(maxDeg > 2) good[nNodes] = true;
  }
  ++nNodes;
}

void dfsLCA(int u){
  for(int v : adj[u]){
    h[v] = h[u] + 1;
    lift[0][v] = u;
    for(int i = 1; i <= 18; ++i){
      lift[i][v] = lift[i - 1][lift[i - 1][v]];
    }
    dfsLCA(v);
  }
}

int getLCA(int u, int v){
  if(h[u] != h[v]){
    if(h[u] < h[v]) swap(u, v);
    for(int i = 18; i >= 0; --i){
      if(h[u] - (1 << i) >= h[v]){
        u = lift[i][u];
      }
    }
  }
  if(u == v) return u;
  for(int i = 18; i >= 0; --i){
    if(lift[i][u] != lift[i][v]){
      u = lift[i][u];
      v = lift[i][v];
    }
  }
  return lift[0][u];
}

int findFirstGood(int u){
  if(good[u]) return u;
  for(int i = 18; i >= 0; --i){
    if(lift[i][u] != -1 and !good[lift[i][u]]){
      u = lift[i][u];
    }
  }
  if(!good[lift[0][u]]) return -1;
  return lift[0][u];
}

void init(int N, int M, vector<int> U, vector<int> V, vector<int> W){
  n = N;
  m = M;
  for(int i = 0; i < m; ++i){
    edges.push_back({U[i], V[i], W[i]});
  }

  memset(lift, -1, sizeof(lift));
  sort(range(edges));
  iota(par, par + n + m, 0);
  nNodes = n;

  for(int i = 0; i < m; ++i){
    int u = edges[i].u, v = edges[i].v, w = edges[i].w;
    ++deg[u]; ++deg[v];
    addEdge(u, v, w, max(deg[u], deg[v]));
  }
  dfsLCA(nNodes - 1);
}

int getMinimumFuelCapacity(int X, int Y){
  int mid = findFirstGood(getLCA(X, Y));
  if(mid == -1) return -1;
  else return weight[mid];
}

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