Submission #994248

#	Time	Username	Problem	Language	Result	Execution time	Memory
994248		vjudge1	Jail (JOI22_jail)	C++17	5 / 100	35 ms	348 KiB

jail

#include <bits/stdc++.h>
using namespace std;

const int maxn = 120'001, mbit = 18;
int n, m;
int dth[maxn];
int S[maxn], T[maxn];
vector <vector <int> > G;
vector <int> w;
vector <vector <int> > g;
vector <vector <int> > stp;

void dfs_lca(int u = 1){
    for(int i = 1; i < mbit; i++){
        stp[u][i] = stp[stp[u][i - 1]][i - 1];
    }
    for(auto v : G[u]){
        if(v != stp[u][0]){
            stp[v][0] = u;
            dth[v] = dth[u] + 1;
            dfs_lca(v);
        }
    }
}

int LCA(int u, int v){
    if(dth[u] < dth[v]) swap(u, v);
    for(int i = mbit - 1; i >= 0; i--){
        if(dth[u] - dth[v] >= (1 << i)) u = stp[u][i];
    }
    if(u == v) return u;
    for(int i = mbit - 1; i >= 0; i--){
        if(stp[u][i] != stp[v][i]){
            u = stp[u][i];
            v = stp[v][i];
        }
    }
    return stp[u][0];
}

bool mid(int u, int v, int M){
    return ((LCA(u, M) == M) || (LCA(v, M) == M)) && (dth[M] >= dth[LCA(u, v)]);
}

bool dfs_loop(int u = 1){
    if(w[u] == 1) return 1;
    if(w[u] == 2) return 0;
    w[u] = 1;
    for(auto v : g[u]){
        if(dfs_loop(v)) return 1;
    }
    w[u] = 2;
    return 0;
}

bool sol(){
    cin >> n;
    G.assign(n + 1, vector<int>());
    stp.assign(n + 1, vector<int>(mbit));
    for(int i = 1; i < n; i++){
        int u, v;
        cin >> u >> v;
        G[u].push_back(v);
        G[v].push_back(u);
    }
    dth[1] = 0;
    dfs_lca();
    //===============
    cin >> m;
    g.assign(m + 1, vector<int>());
    for(int i = 0; i < m; i++){
        cin >> S[i] >> T[i];
    }
    for(int i = 0; i < m; i++){
        for(int j = 0; j < m; j++){
            if(i == j) continue;
            if(mid(S[i], T[i], S[j])) g[i].push_back(j);
            if(mid(S[i], T[i], T[j])) g[j].push_back(i);
        }
    }
    w.assign(m + 1, 0);
    return !dfs_loop();
}

int main(){
    int Q;
    cin >> Q;
    while(Q--){
        cout << (sol() ? "Yes" : "No") << endl;
    }
    return 0;
}

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