Submission #776222

#	Time	Username	Problem	Language	Result	Execution time	Memory
776222		eltu0815	Jail (JOI22_jail)	C++14	0 / 100	2 ms	3156 KiB

jail

#include <bits/stdc++.h>
#define MAX 500005
#define MOD (ll)(1e9+7)
#define INF (ll)(1e18)
 
using namespace std;    
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
 
int n, m, tt;
int parent[120005][25];
int s[120005], t[120005], dep[120005];
vector<int> graph[120005];

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    
    cin >> tt;
    while(tt--) {
        cin >> n;
        for(int i = 1; i <= n; ++i) graph[i].clear();
        for(int i = 1; i <= n; ++i) for(int j = 0; j <= 20; ++j) parent[i][j] = 0;
        for(int i = 1; i <= n - 1; ++i) {
            int a, b; cin >> a >> b;
            graph[a].push_back(b);
            graph[b].push_back(a);
        }
        
        cin >> m;
        for(int i = 1; i <= m; ++i) cin >> s[i] >> t[i];
        
        auto dfs = [=](auto&& self, int node, int par) -> void {
            parent[node][0] = par; dep[node] = dep[par] + 1;
            for(auto v : graph[node]) if(v != par) self(self, v, node);
        };
        dfs(dfs, 1, 0);
        for(int j = 1; j < 20; ++j) for(int i = 1; i <= n; ++i) parent[i][j] = parent[parent[i][j - 1]][j - 1];
        
        auto LCA = [=](int u, int v) -> int {
            if(dep[u] < dep[v]) swap(u, v);
            int diff = dep[u] - dep[v], j = 0;
            while(diff) {
                if(diff & 1) u = parent[u][j];
                diff >>= 1; ++j;
            }
            if(u == v) return u;
            for(int i = 19; i >= 0; --i) {
                if(parent[u][i] != parent[v][i]) {
                    u = parent[u][i];
                    v = parent[v][i];
                }
            }
            return parent[u][0];
        };
        
        auto path = [=](int s, int t, int n) -> bool {
            while(s != t) {
                if(s == n) return false;
                s = parent[s][0];
            }
            return s == n;
        };
        
        auto chk = [=](int s1, int t1, int s2, int t2) -> bool {
            int p1 = LCA(s1, t1), p2 = LCA(s2, t2);
            if(!path(s1, p1, s2) || !path(t1, p1, s2)) return false;
            if(!path(s2, p2, t1) || !path(t2, p2, t1)) return false;
            return true;
        };
        
        if(chk(s[1], t[1], s[2], t[2]) || chk(s[2], t[2], s[1], t[1])) cout << "YES\n";
        else cout << "NO\n";
    }
    
    return 0;
}

• 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