Submission #777341

#	Time	Username	Problem	Language	Result	Execution time	Memory
777341		ETO_leader	Regions (IOI09_regions)	C++17	0 / 100	6943 ms	131072 KiB

regions

#include<bits/stdc++.h>
#define cir(i,a,b) for(int i=a;i<b;++i)
using namespace std;
using VI=vector<int>;
vector<VI> G,cx,ck;
VI tin,tout,vis,col;
void dfs(int u,int&cnx,int f=0){
    tin[u]=cnx++;
    for(auto&i:G[u]) if(i!=f) dfs(i,cnx,u);
    tout[u]=cnx;
}
bool isancestor(int u,int v){
    return tin[u]<=tin[v]&&tout[v]<=tout[u];
}
void dfsx(int u,int id,int f=0){
    if(vis[u]) return;
    vis[u]=true;cx[id][col[u]]++;
    for(auto&i:G[u]) if(i!=f) dfsx(i,id,u);
}
void init(int n){
    G.resize(n+1);tin.resize(n+1);col.resize(n+1);
    tout.resize(n+1);vis.resize(n+1);
}
int main(){
    ios::sync_with_stdio(false),cin.tie(0);
    int n,r,q;cin>>n>>r>>q;init(n);
    const int sqr=pow<double>(n,3.0/1.0)+1;
    VI cnx(r+1),idx(n+1);
    vector<VI> ci(r+1);
    cin>>col[1];cnx[col[1]]++;ci[col[1]].push_back(1);
    cir(i,2,n+1){
        int f;cin>>f>>col[i];cnx[col[i]]++;
        G[f].push_back(i);G[i].push_back(f);
        ci[col[i]].push_back(i);
    }
    [&](){int ncnx=0;dfs(1,ncnx);}();
    cir(i,1,r+1) if(col[i]>sqr){
        idx[i]=cx.size();cx.push_back(VI(r+1));
        fill(vis.begin(),vis.end(),false);
        for(auto&j:ci[i]) dfsx(j,idx[i]);
        ck.push_back(VI(r+1));
        cir(j,1,r+1) ck[idx[i]][j]=cnx[j]-cx[idx[i]][j];
    }
    cir(i,1,r+1) sort(ci[i].begin(),ci[i].end(),
        [&](int a,int b){return tin[a]<tin[b];});
    auto bfdis=[&](int c1,int c2){
        int res=0;
        unordered_set<int> ch;
        for(auto&i:ci[c1]) for(auto&j:ci[c2]){
            if(!ch.count(j)) res+=isancestor(i,j);
            if(isancestor(i,j)) ch.insert(j);
        }
        return res;
    };
    cir(i,0,q){
        int r1,r2;cin>>r1>>r2;
        if(cnx[r1]>sqr) cout<<cx[idx[r1]][r2]<<'\n';
        else if(cnx[r2]>sqr) cout<<ck[idx[r2]][r1]<<'\n';
        else cout<<bfdis(r1,r2)<<'\n';
        cout.flush();
    }
    return 0;
}

• Subtask 1: 0 / 15
• Subtask 2: 0 / 85