Submission #335387

#	Time	Username	Problem	Language	Result	Execution time	Memory
335387		blue	Power Plant (JOI20_power)	C++11	0 / 100	6 ms	8172 KiB

power

#include <iostream>
#include <vector>
#include <queue>
#include <deque>
using namespace std;

int N;
vector<int> edge[200001];
vector<int> plant(200000);
vector<int> edge_count(200001, 0);
vector<int> stream_count(200001, 0);
vector<int> visit(200001, 0);

int res = 0;

int main()
{
    cin >> N;

    int a, b;

    for(int i = 1; i <= N-1; i++)
    {
        cin >> a >> b;

        edge[a].push_back(b);
        edge_count[a]++;

        edge[b].push_back(a);
        edge_count[b]++;
    }

    char c;
    for(int i = 1; i <= N; i++)
    {
        cin >> c;
        plant[i] = (c == '1');
    }

    deque<int> tbv1, tbv2;
    for(int i = 1; i <= N; i++) if(edge_count[i] == 1)
    {
        if(plant[i]) tbv1.push_front(i);
        else tbv1.push_back(i);
    }

    while(!(tbv1.empty() && tbv2.empty()))
    {
        a = tbv1.front();
        tbv1.pop_front();
        if(visit[a]) continue;
        visit[a] = 1;

        for(int v: edge[a])
        {
            if(!visit[v])
            {
                edge_count[v]--;
                if(edge_count[v] <= 1)
                {
                    if(plant[v]) tbv2.push_front(v);
                    else tbv2.push_back(v);
                }
            }
            else
            {
                stream_count[a] += stream_count[v];
            }
        }
        if(stream_count[a] > 1 && plant[a]) res--;
        if(stream_count[a] == 0 && plant[a])
        {
            stream_count[a]++;
            res++;
        }
        if(tbv1.empty()) swap(tbv1, tbv2);
    }
    cout << res << '\n';
    return 0;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 0 / 53