Submission #340189

#	Time	Username	Problem	Language	Result	Execution time	Memory
340189		blue	Bosses (BOI16_bosses)	C++11	100 / 100	958 ms	620 KiB

bosses

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

/*
    S[i] = sum{j in children[i], S[j]} + 1

    => S[leaf] = 0

    Every non-leaf i contributes depth[i] to the total sum by increasing each of its ancestors and itself by 1

    So, answer = sum{i not a leaf, depth[i]}
    Do a BFS to find minimum depths. Try out every vertex as root once.
*/

int main()
{
    int n;
    cin >> n;

    vector<int> next[n+1];

    int a, b;
    for(int i = 1; i <= n; i++)
    {
        cin >> a;
        for(int j = 1; j <= a; j++)
        {
            cin >> b;
            next[b].push_back(i);
        }
    }

    int res = 2000000000, r;

    vector<int> S(n+1);
    queue<int> tbv, dist;

    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= n; j++) S[j] = 0;
        S[i] = 1;
        r = 1;
        tbv.push(i);
        dist.push(1);
        while(!tbv.empty())
        {
            for(int j:next[tbv.front()])
            {
                if(S[j]) continue;
                S[j] = dist.front() + 1;
                r += dist.front() + 1;
                dist.push(dist.front() + 1);
                tbv.push(j);
            }
            tbv.pop();
            dist.pop();
        }
        for(b = 1; b <= n; b++) if(S[b] == 0) break;
        if(b <= n) continue;
        res = min(res, r);
    }
    cout << res << '\n';
    return 0;
}

• Subtask 1: 22 / 22
• Subtask 2: 45 / 45
• Subtask 3: 33 / 33