Submission #547101

#	Time	Username	Problem	Language	Result	Execution time	Memory
547101		cig32	Swapping Cities (APIO20_swap)	C++17	6 / 100	228 ms	69180 KiB

swap

#include "bits/stdc++.h"
using namespace std;
//#define int long long
const int MAXN = 2e5 + 10;
const int MOD = 1e9 + 7;
#define ll __int128
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
ll read() { // read int128
  int x; cin >> x; return (ll)x;
}
long long bm(long long b, long long p) {
  if(p==0) return 1 % MOD;
  long long r = bm(b, p >> 1);
  if(p&1) return (((r*r) % MOD) * b) % MOD;
  return (r*r) % MOD;
}
long long inv(long long b) { 
  return bm(b, MOD-2);
}
long long f[MAXN];
long long nCr(int n, int r) { 
  long long ans = f[n]; ans *= inv(f[r]); ans %= MOD;
  ans *= inv(f[n-r]); ans %= MOD; return ans;
}
void precomp() { 
  for(int i=0; i<MAXN; i++) f[i] = (i == 0 ? 1 % MOD : (f[i-1] * i) % MOD);
}
int fastlog(int x) {
  if(x == 0) return -1;
  return 32 - __builtin_clz(x) - 1;
}
void gay(int i) {
  cout << "Case #" << i << ": ";
}
#include "swap.h"
void init(int N, int M, std::vector<int> U, std::vector<int> V, std::vector<int> W);

int getMinimumFuelCapacity(int X, int Y);

int n, m;
vector<pair<int,int> > adj[101010];
struct edge {
  int f, t, w;
};
class cmp {
  public:
  bool operator() (edge x, edge y) {
    return x.w>y.w;
  }
};
vector<edge> mst;
edge e[101010];
int dsu[101010];
int set_of(int u) {
  if(dsu[u]==u) return u;
  return dsu[u]= set_of(dsu[u]);
}
void union_(int u, int v) {
  dsu[set_of(u)] = set_of(v);
}
struct node {
  vector<int> a; // children
  int par; // parenty
  int blackw, greenw; // minimum weight limit s.t. subtree is pairwise reachable
  int madeg = 0; // max degree
} krt[202020];
int rep[202020];
int root;
vector<int> euler;
int dep[202020];
int fuck[202020];
void dfs(int node, int prv) {
  euler.push_back(node);
  dep[node] = (prv == -1 ? 0 : dep[prv] + 1);
  fuck[node] = min(krt[node].greenw, (prv == -1 ? (int)2e9 : fuck[prv]));
  for(int x: krt[node].a) {
    if(x != prv) {
      dfs(x, node);
      euler.push_back(x);
    }
  }
}
int l[202020], r[202020];
pair<int,int> st[19][202020];
int lca_idx(int x, int y) {
  int m1 = min(l[x], l[y]);
  int m2 = max(r[x], r[y]);
  int k = 32 - __builtin_clz(m2-m1 + 1) - 1;
  return min(st[k][m1], st[k][m2 - (1<<k) + 1]).second;
}
void init(int N, int M, std::vector<int> U, std::vector<int> V, std::vector<int> W) {
  n = N, m = M;
  for(int i=0; i<m; i++) {
    adj[U[i]].push_back({V[i], W[i]});
    adj[V[i]].push_back({U[i], W[i]});
    e[i] = {U[i], V[i], W[i]};
  }
  for(int i=0; i<n; i++) dsu[i] = i;
  priority_queue<edge, vector<edge>, cmp> pq;
  for(int i=0; i<m; i++) pq.push(e[i]);
  int newnode = n;
  for(int i=0; i<n; i++) rep[i] = i;
  for(int i=0; i<202020; i++) krt[i].blackw = 0, krt[i].greenw = 2e9, krt[i].par = -1;
  int deg[n];
  for(int i=0; i<n; i++) deg[i] = 0;
  // Conditions: either cycle or max degree ≥ 3 (i.e. NOT chain)
  while(pq.size()) {
    deg[pq.top().f]++;
    deg[pq.top().t]++;
    if(set_of(pq.top().f) != set_of(pq.top().t)) {
      int st1 = rep[set_of(pq.top().f)];
      int st2 = rep[set_of(pq.top().t)];
      krt[newnode].a.push_back(st1);
      krt[newnode].a.push_back(st2);
      krt[st1].par = krt[st2].par = newnode;
      union_(pq.top().f, pq.top().t);
      rep[set_of(pq.top().f)] = newnode;
      krt[newnode].madeg = max({krt[st1].madeg, krt[st2].madeg, deg[pq.top().f], deg[pq.top().t]});
      krt[newnode].blackw = pq.top().w;
      if(krt[newnode].madeg >= 3 || krt[st1].greenw != 2e9 || krt[st2].greenw != 2e9) {
        krt[newnode].greenw = pq.top().w;
      }
      else {
        krt[newnode].greenw = 2e9;
      }
      newnode++;
    }
    else { // update all the way to the root, update max degree array and green weights
      int rt = rep[set_of(pq.top().f)];
      //cout << "root = " << rt << "\n";
      if(krt[rt].greenw == 2e9) { // O(component size) is ok
        int now = pq.top().f;
        unordered_map<int, int> vis;
        while(now != rt) {
          now = krt[now].par;
          vis[now] = 1;
        }
        now = pq.top().t;
        while(now != rt) {
          now = krt[now].par;
          if(vis[now]) {
            // common ancestor
            krt[now].greenw = pq.top().w;
          }
        }
      }

    }
    pq.pop();
  }
  root = newnode - 1;
  /*
  for(int i=newnode - 1; i >= 0; i--) {
    cout << "node " << i << ": black = " << krt[i].blackw << ", green = " << krt[i].greenw << ", max degree = " << krt[i].madeg << "\n";
    for(int x: krt[i].a) cout << i << " " << x << "\n";

  }
  */
  dfs(root, -1);
  for(int i=0; i<euler.size(); i++) r[euler[i]] = i;
  for(int i=euler.size()-1; i>=0; i--) l[euler[i]] = i;
  for(int i=0; i<euler.size(); i++) st[0][i] = {dep[euler[i]], euler[i]};
  for(int i=1; i<19; i++) {
    for(int j=0; j<euler.size(); j++) {
      if(j+(1<<i)-1 < euler.size()) st[i][j] = min(st[i-1][j], st[i-1][j+(1<<(i-1))]);
    }
  }
}
int getMinimumFuelCapacity(int X, int Y) {
  int q = lca_idx(X, Y);
  return (fuck[q] == 2e9 ? -1 : fuck[q]);
}

Compilation message (stderr)

swap.cpp: In function 'void init(int, int, std::vector<int>, std::vector<int>, std::vector<int>)':
swap.cpp:163:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  163 |   for(int i=0; i<euler.size(); i++) r[euler[i]] = i;
      |                ~^~~~~~~~~~~~~
swap.cpp:165:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  165 |   for(int i=0; i<euler.size(); i++) st[0][i] = {dep[euler[i]], euler[i]};
      |                ~^~~~~~~~~~~~~
swap.cpp:167:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  167 |     for(int j=0; j<euler.size(); j++) {
      |                  ~^~~~~~~~~~~~~
swap.cpp:168:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  168 |       if(j+(1<<i)-1 < euler.size()) st[i][j] = min(st[i-1][j], st[i-1][j+(1<<(i-1))]);
      |          ~~~~~~~~~~~^~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 0 / 7
• Subtask 3: 0 / 17
• Subtask 4: 0 / 20
• Subtask 5: 0 / 23
• Subtask 6: 0 / 27