Submission #983042

#	Time	Username	Problem	Language	Result	Execution time	Memory
983042		shenfe1	Swapping Cities (APIO20_swap)	C++17	100 / 100	370 ms	84196 KiB

swap

#include "swap.h"
#include <bits/stdc++.h>
 
#pragma optimize("Ofast")
#pragma target("avx2")
 
using namespace std;
 
#define ll long long
#define ld long double
#define pb push_back
#define pf push_front
#define pii pair<int,int>
#define all(v) v.begin(),v.end()
#define F first
#define S second
#define mem(a,i) memset(a,i,sizeof(a))
#define sz(s) (int)s.size()
#define y1 yy
#define ppb pop_back
#define lb lower_bound
#define ub upper_bound
#define gcd(a,b) __gcd(a,b)
#define in insert

const int MAX=1e6+15;
const int B=300;
const int N=104;
const int block=400;
const int maxB=MAX/B+10;
const ll inf=2e9;  
const int mod=998244353;
const int mod1=1e9+9;
const ld eps=1e-9;
 
int dx[8]={1,0,-1,0,1,-1,-1,1};
int dy[8]={0,1,0,-1,1,-1,1,-1};
 
int binpow(int a,int n){
  if(!n)return 1;
  if(n%2==1)return a*binpow(a,n-1)%mod;
  int k=binpow(a,n/2);
  return k*k%mod;
}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n;
int mark[MAX];
int cost[MAX];
vector<int> g[MAX];

struct DSU{
  int f[MAX];
  int cur;

  void init(int n,int ver){
    cur=ver;
    for(int i=1;i<=n;i++)f[i]=i;
  }

  int get(int v){
    return (f[v]==v?v:f[v]=get(f[v]));
  }

  void unite(int a,int b,bool is,int C){
    a=get(a);
    b=get(b);
    int x=++cur;
    g[x].pb(a);
    g[x].pb(b);
    // cout<<x<<" "<<a<<"\n";
    // cout<<x<<" "<<b<<"\n";
    mark[x]=is;
    cost[x]=C;
    f[a]=f[b]=x;
  }

  void cycle(int a,int C){
    a=get(a);
    int x=++cur;
    cost[x]=C;
    g[x].pb(a);
    // cout<<x<<" "<<a<<"\n";
    mark[x]=1;
    f[a]=x;
  }
}D;

int up[MAX][20];
int tin[MAX],tout[MAX],timer;
int cnt[MAX];
int mn[MAX];
int deg[MAX];

void dfs(int v,int p){
  tin[v]=++timer;
  up[v][0]=p;
  // cout<<v<<" "<<p<<"\n";
  for(int i=1;i<20;i++)up[v][i]=up[up[v][i-1]][i-1];
  for(auto to:g[v]){
    if(to==p)continue;
    mn[to]=min(mn[to],mn[v]);
    dfs(to,v);
  }
  tout[v]=timer;
}

void dfs1(int v,int p){
  cnt[v]=mark[v];
  for(auto to:g[v]){
    if(to==p)continue;
    dfs1(to,v);
    cnt[v]+=cnt[to];
  }
  if(cnt[v])mn[v]=cost[v];
}

void init(int N, int M,vector<int> U,vector<int> V,vector<int> W) {
  D.init(N+M,N);
  vector<pair<int,pii>> e;
  for(int i=0;i<M;i++){
    U[i]++;V[i]++;
    e.pb({W[i],{U[i],V[i]}});
  }
  sort(all(e));
  for(auto x:e){
    int w=x.F;
    int u=x.S.F;
    int v=x.S.S;
    // cerr<<w<<" "<<u<<" "<<v<<"\n";
    if(D.get(u)!=D.get(v)){
      deg[u]++;
      deg[v]++;
      bool is=(deg[u]==3||deg[v]==3);
      D.unite(u,v,is,w);
      // cout<<u<<" "<<v<<" "<<D.get(u)<<" "<<D.get(v)<<"\n";
    }
    else{
      D.cycle(u,w);
      // cout<<D.cur<<" "<<w<<"\n";
    }
  }
  // cerr<<1<<"\n";
  for(int i=1;i<=D.cur;i++){
    mn[i]=inf;
  }
  dfs1(D.get(1),D.get(1));
  dfs(D.get(1),D.get(1));
}

int par(int a,int b){
  return (tin[a]<=tin[b]&&tout[b]<=tout[a]);
}

int lca(int a,int b){
  if(par(a,b))return a;
  if(par(b,a))return b;
  for(int i=19;i>=0;i--){
    if(!par(up[a][i],b)){
      a=up[a][i];
    }
  }
  return up[a][0];
}

int getMinimumFuelCapacity(int X, int Y) {
  X++;
  Y++;
  int l=lca(X,Y);
  if(max(min(mn[X],mn[Y]),cost[l])==inf)return -1;
  return max(min(mn[X],mn[Y]),cost[l]);
}

Compilation message (stderr)

swap.cpp:4: warning: ignoring '#pragma optimize ' [-Wunknown-pragmas]
    4 | #pragma optimize("Ofast")
      | 
swap.cpp:5: warning: ignoring '#pragma target ' [-Wunknown-pragmas]
    5 | #pragma target("avx2")
      |

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