Submission #379752

#	Time	Username	Problem	Language	Result	Execution time	Memory
379752		cgiosy	Mergers (JOI19_mergers)	C++17	0 / 100	70 ms	7416 KiB

mergers

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

int main() {
	ios::sync_with_stdio(0);cin.tie(0);
	int N, M, ans=0, t=0;
	cin>>N>>M;
	vector<int> C(N), L(M), R(M);
	vector<vector<int>> G(N);
	for(int i=1; i<N; i++) {
		int x, y;
		cin>>x>>y; --x, --y;
		G[x].push_back(y);
		G[y].push_back(x);
	}
	for(int i=0; i<N; i++) cin>>C[i], --C[i];

	function<void(int, int)> f=[&](int i, int p) {
		++t;
		L[C[i]]=L[C[i]]?:t;
		for(int j:G[i]) if(j!=p) f(j, i);
		R[C[i]]=t;
	};
	f(0, 0);

	t=0;
	function<pair<int, int>(int, int)> g=[&](int i, int p) {
		++t;
		int a=L[C[i]], b=R[C[i]], s=t;
		for(int j:G[i]) if(j!=p) {
			auto[c,d]=g(j, i);
			a=min(a, c);
			b=max(b, d);
		}
		if(s<=a && b<=t) ans++, a=0;
		return make_pair(a, b);
	};
	for(int i=0; i<N; i++) if(G[i].size()<2) { g(i, i); break; }

	cout<<ans/2<<'\n';
}

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