Submission #122060

#	Time	Username	Problem	Language	Result	Execution time	Memory
122060		Rudy420	Mergers (JOI19_mergers)	C++17	0 / 100	109 ms	25200 KiB

mergers

#include <bits/stdc++.h>
using namespace std;
#define x first
#define y second
#define ll long long
#define pi pair<int,int>
#define pl pair<ll,ll>
#define pd pair<double,double>
#define ld long double
#define pld pair<ld,ld>
#define lg length()
#define sz size()
#define vi vector<int>
#define vl vector<ll>
#define vp vector<pi>
#define vpl vector<pl>
#define pb push_back
#define INF 1000000005
#define LINF 1000000000000000005
#define eps 0.001
#ifdef LOCAL_DEFINE
    mt19937 rng(69);
#else
    seed_seq seq{
        (uint64_t) chrono::duration_cast<chrono::nanoseconds>(chrono::high_resolution_clock::now().time_since_epoch()).count(),
        //(uint64_t) __builtin_ia32_rdtsc(),
        //(uint64_t) (uintptr_t) make_unique<char>().get()
    };
    mt19937 rng(seq);
#endif

int n,k,x,y,a[500005],p[20][500005],h[500005],lca[500005],ans,mn[500005];

vi g[500005];

void DFS1(int nod, int par, int hg){
	h[nod]=hg;
	p[0][nod]=par;
	for(int i=1;i<20;i++){
		p[i][nod]=p[i-1][p[i-1][nod]];
	}
	for(int i : g[nod]){
		if(i!=par){
			DFS1(i,nod,hg+1);
		}
	}
}

int LCA(int x, int y){
	if(h[x]<h[y]) swap(x,y);
	for(int i=19;i>=0;i--){
		if(h[p[i][x]]>=h[y]) x=p[i][x];
	}
	if(x==y) return x;
	for(int i=19;i>=0;i--){
		if(p[i][x]!=p[i][y]) x=p[i][x],y=p[i][x];
	}
	return p[0][x];
}

int DFS2(int nod, int par){
	mn[nod]=h[lca[a[nod]]];
	int gd=0;
	for(int i : g[nod]){
		if(i!=par){
			gd=max(gd,DFS2(i,nod));
			mn[nod]=min(mn[nod],mn[i]);
		}
	}
	if(mn[nod]==h[nod] && !gd && nod!=1) ans++,gd=1;
	return gd;
}

int32_t main(){
#ifdef LOCAL_DEFINE
    ifstream cin("input.txt");
#endif
    ios_base :: sync_with_stdio(0); cin.tie(); cout.tie();
    cin >> n >> k;
    for(int i=1;i<n;i++){
    	cin >> x >> y;
    	g[x].pb(y);
    	g[y].pb(x);
	}
	DFS1(1,-1,1);
	for(int i=1;i<=n;i++){
		cin >> a[i];
		if(!lca[a[i]]) lca[a[i]]=i;
		else lca[a[i]]=LCA(lca[a[i]],i);
	}
	DFS2(1,-1);
	cout << (ans+1)/2;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30