Submission #1243464

#	Time	Username	Problem	Language	Result	Execution time	Memory
1243464		Aviansh	Jail (JOI22_jail)	C++20	5 / 100	74 ms	14408 KiB

jail

#include <bits/stdc++.h>

using namespace std;

unordered_set<int>sfin;
unordered_set<int>tfin;

void dfs(int st, vector<int>g[], int p, int d, int dep[], int par[]){
    par[st]=p;
    dep[st]=d;
    for(int i : g[st]){
        if(i==p)
            continue;
        dfs(i,g,st,d+1,dep,par);
    }
}

void finder(int s, int t, int revs[], int revt[], int dep[], int par[]){
    sfin.clear();
    tfin.clear();
    while(s!=t){
        if(dep[s]<dep[t]){
            swap(s,t);
        }
        //s is deeper now
        sfin.insert(revs[s]);
        tfin.insert(revt[s]);
        s=par[s];
    }
    sfin.insert(revs[s]);
    tfin.insert(revt[s]);
}
bool cyc;
void checkcyc(int st, vector<int>g[], int vis[]){
    vis[st]=1;
    for(int i : g[st]){
        if(vis[i]==1){
            cyc=1;
        }
        if(vis[i])
            continue;
        checkcyc(i,g,vis);
    }
    vis[st]=2;
}

void solve(){
    int n;
    cin >> n;
    vector<int>g[n];
    for(int i = 0;i<n-1;i++){
        int a,b;
        cin >> a >> b;
        a--;b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    int m;
    cin >> m;
    int s[m],t[m];
    int revs[n],revt[n];
    fill(revs,revs+n,-1);
    fill(revt,revt+n,-1);
    for(int i = 0;i<m;i++){
        cin >> s[i] >> t[i];
        s[i]--;
        t[i]--;
        revs[s[i]]=i;
        revt[t[i]]=i;
    }

    //line case.
    set<array<int,2>>forw;
    set<array<int,2>>bac;
    for(int i = 0;i<m;i++){
        if(s[i]<t[i]){
            forw.insert({s[i],t[i]});
        }
        else{
            bac.insert({-s[i],-t[i]});
        }
    }
    int las = -1;
    for(array<int,2>a:forw){
        if(a[1]<las){
            cout << "No\n";
            return;
        }
        las=a[1];
    }
    las=-1e9;
    for(array<int,2>a:bac){
        if(a[1]<las){
            cout << "No\n";
            return;
        }
        las=a[1];
    }
    for(int i = 0;i<m;i++){
        if(s[i]<t[i]){
            continue;
        }
        swap(s[i],t[i]);
        //check for intersections.
        auto it = forw.upper_bound({s[i],1000000000});
        if(it!=forw.end()){
            if((*it)[0]<=t[i]){
                cout << "No\n";
                return;
            }
        }
        if(it!=forw.begin()){
            it--;
            if((*it)[1]>=s[i]){
                cout << "No\n";
                return;
            }
        }
    }
    cout << "Yes\n";
    return;

    unordered_set<int>spath[m];
    unordered_set<int>tpath[m];
    int dep[n];
    int par[n];
    dfs(0,g,-1,0,dep,par);
    for(int i = 0;i<m;i++){
        finder(s[i],t[i],revs,revt,dep,par);
        for(int j : sfin){
            spath[i].insert(j);
        }
        for(int j : tfin){
            tpath[i].insert(j);
        }
    }
    vector<int>g2[m];
    for(int i = 0;i<m;i++){
        for(int j : spath[i]){
            if(j==-1||j==i){
                continue;
            }
            g2[j].push_back(i);
        }
        for(int j : tpath[i]){
            if(j==-1||j==i){
                continue;
            }
            g2[i].push_back(j);
        }
    }
    //now check for cycle.
    cyc=0;
    int vis[m];
    fill(vis,vis+m,0);
    for(int i = 0;i<m;i++){
        if(vis[i]==0){
            checkcyc(i,g2,vis);
        }
    }
    for(bool i : vis){
        if(!i){
            cyc=1;
        }
    }
    if(cyc){
        cout << "No\n";
    }
    else{
        cout << "Yes\n";
    }
}

signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    while(t--){
        solve();
    }
    return 0;
}

• Subtask 1: 5 / 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