Submission #546958

#	Time	Username	Problem	Language	Result	Execution time	Memory
546958		ngrace	Jail (JOI22_jail)	C++14	0 / 100	1 ms	212 KiB

jail

#include <vector>
#include <iostream>
#include <utility>
#include <set>
#include <algorithm>
using namespace std;
#define v vector
#define pii pair<int,int>
#define fi first
#define se second
 
int N,M;
int anc=20;
v<v<int>> adj;
v<int> depth;
v<v<int>> par;
v<int> ps;
v<int> pe;
v<v<int>> num;
void dfs(int cur, int from){
    if(depth[cur]!=-1) return;
    depth[cur]=depth[from]+1;
    par[cur][0]=from;
    if(ps[cur]!=-1) num[cur][0]++;
    if(pe[cur]!=-1) num[cur][0]++;
    for(int it:adj[cur]) dfs(it, cur);
}
bool is_anc(int cur, int other){
    for(int i=anc-1; i>=0; i--){
        if(depth[par[cur][i]]>=depth[other]) cur=par[cur][i];
    }
    if(cur==other) return true;
    return false;
}
 
int lca(int a, int b){
    if(depth[a]<depth[b]) swap(a,b);
    for(int i=anc-1; i>=0; i--){
        if(depth[par[a][i]]>=depth[b]) a=par[a][i];
    }
    if(a==b) return a;
    for(int i=anc-1; i>=0; i--){
        if(par[a][i]!=par[b][i]){
            a=par[a][i];
            b=par[b][i];
        }
    }
    return par[a][0];
}
 
v<bool> prevrec;
v<bool> vis;
bool find_cycle(int cur){
    if(!vis[cur]){
        vis[cur]=true;
        prevrec[cur]=true;
        for(int it:adj[cur]){
            if(!vis[it] && find_cycle(it)){
                return true;
            }
            else if(prevrec[it]){
                return true;
            }
        }
    }
    prevrec[cur]=false;
    return false;
}
 
int main(){
    int Q;
    cin>>Q;
    for(int q=0;q<Q;q++){
        cin>>N;
        adj=v<v<int>>(N);
        for(int i=0; i<N-1; i++){
            int a,b;
            cin>>a>>b;
            a--;
            b--;
            adj[a].push_back(b);
            adj[b].push_back(a);
        }
 
        cin>>M;
        v<pii> rooms(M);
        ps = v<int>(N,-1);
        pe = v<int>(N,-1);
        for(int i=0; i<M; i++){
            cin>>rooms[i].fi>>rooms[i].se;
            rooms[i].fi--;
            rooms[i].se--;
            ps[rooms[i].fi]=i;
            pe[rooms[i].se]=i;
        }


        depth=v<int>(N,-1);
        par=v<v<int>>(N,v<int>(anc,-1));
        num=v<v<int>>(N,v<int>(anc,0));
        dfs(0,0);
        for(int i=1; i<anc; i++){
            for(int j=0; j<N; j++){
                par[j][i]=par[par[j][i-1]][i-1];
                num[j][i]=num[par[j][i-1]][i-1]+num[j][i-1];
            }
        }

 
        adj = v<v<int>>(M);
        for(int i=0; i<M; i++){
            int a=rooms[i].fi;
            int b=rooms[i].se;
            int l=lca(a,b);

            //if have quick way of checking if any are on the path between x and an ancestor of x then can do the while loops below faster with binary lifting
            while(true){
                for(int j=anc-1; j>=0; j--){
                    if(depth[par[a][j]]<depth[l]) continue;
                    if(num[a][j]==0) a=par[a][j];
                }
                if(a==0) break;
                if(ps[a]!=-1 && ps[a]!=i) adj[ps[a]].push_back(i);
                if(pe[a]!=-1 && pe[a]!=i) adj[i].push_back(pe[a]);
                if(a==l) break;
                a=par[a][0];
            }
            while(b!=l){
                for(int j=anc-1; j>=0; j--){
                    if(depth[par[b][j]]<=depth[l]) continue;
                    if(num[b][j]==0) b=par[b][j];
                }
                if(b==0) break;
                if(ps[b]!=-1 && ps[b]!=i) adj[ps[b]].push_back(i);
                if(pe[b]!=-1 && pe[b]!=i) adj[i].push_back(pe[b]);
                b=par[b][0];
            }
        }

        bool cycle=false;
        vis = v<bool>(M,false);
        prevrec = v<bool>(M,false);
        for(int i=0; i<M; i++){
            if(!vis[i] && find_cycle(i)){
                cycle=true;
                break;
            }
        }
 
        if(cycle) cout<<"No\n";
        else cout<<"Yes\n";
    }
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 16
• Subtask 4: 0 / 28
• Subtask 5: 0 / 12
• Subtask 6: 0 / 11
• Subtask 7: 0 / 23