Submission #876765

#	Time	Username	Problem	Language	Result	Execution time	Memory
876765		serkanrashid	Jail (JOI22_jail)	C++14	61 / 100	5051 ms	30020 KiB

jail

#include <bits/stdc++.h>
#define endl "\n"

using namespace std;

const int maxn = 12*1e4+5;

int q,n,m;
vector<int>g[maxn],v[maxn];
int s[maxn],t[maxn],used[maxn];
int jump[maxn][21],lvl[maxn];
bool ans;

void precom()
{
    for(int i=1;i<=n;i++)
    {
        g[i].clear();
        used[i] = 0;
        v[i].clear();
    }
}

void read()
{
    cin >> n;
    precom();
    int a,b;
    for(int i=1;i<n;i++)
    {
        cin >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    cin >> m;
    for(int i=1;i<=m;i++)
    {
        cin >> s[i] >> t[i];
    }
}

void dfs_make(int beg, int par)
{
    jump[beg][0] = par;
    lvl[beg] = lvl[par] + 1;
    for(int nb:g[beg]) if(nb!=par) dfs_make(nb,beg);
}

void make_lca()
{
    lvl[1] = 0;
    dfs_make(1,1);
    for(int j=1;j<=20;j++)
    {
        for(int i=1;i<=n;i++)
        {
            jump[i][j] = jump[jump[i][j-1]][j-1];
        }
    }
}

int get_lca(int a, int b)
{
    int raz = abs(lvl[a]-lvl[b]);
    for(int j=20;j>=0;j--)
    {
        if(raz&(1<<j))
        {
            if(lvl[a]>lvl[b]) a = jump[a][j];
            else b = jump[b][j];
        }
    }
    if(a==b) return a;
    for(int j=20;j>=0;j--)
    {
        if(jump[a][j]!=jump[b][j])
        {
            a = jump[a][j];
            b = jump[b][j];
        }
    }
    return jump[a][0];
}

bool check(int a, int b, int c)
{
    int lca = get_lca(a,b);
    if(get_lca(c,lca)!=lca) return false;
    return (get_lca(c,a)==c || get_lca(c,b) == c);
}

void dfs(int beg)
{
    used[beg] = 1;
    for(int nb:v[beg])
    {
        if(used[nb]==1) ans = false;
        if(!used[nb]) dfs(nb);
    }
    used[beg] = 2;
}

void solve()
{
    make_lca();
    for(int i=1;i<=m;i++)
    {
        for(int j=1;j<=m;j++)
        {
            if(i==j) continue;
            int chis = 0;
            if(check(s[i],t[i],s[j])) chis += 2;
            if(check(s[i],t[i],t[j])) chis += 1;
            if((chis&2)) v[j].push_back(i);
            if((chis&1)) v[i].push_back(j);
        }
    }
    ans = true;
    for(int i=1;i<=m;i++) used[i] = 0;
    for(int i=1;i<=m;i++)
    {
        if(!used[i]) dfs(i);
    }
    if(ans) cout << "Yes" << endl;
    else cout << "No" << endl;
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> q;
	for(int i=1;i<=q;i++)
    {
        read();
        solve();
    }
return 0;
}
/*
1
8
1 2
2 3
3 4
4 5
5 6
6 7
7 8
4
1 5
2 6
3 7
4 8
*/

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