Submission #1103049

#	Time	Username	Problem	Language	Result	Execution time	Memory
1103049		alexdd	Cat in a tree (BOI17_catinatree)	C++17	51 / 100	1064 ms	17128 KiB

catinatree

#include <bits/stdc++.h>
using namespace std;
int n,d,root;
vector<int> con[200005];
int parent[200005],depth[200005],injos[200005];
void dfs(int nod)
{
    for(int adj:con[nod])
    {
        if(adj==parent[nod])
            continue;
        parent[adj] = nod;
        depth[adj] = depth[nod]+1;
        dfs(adj);
    }
}
bool verif(int nod)
{
    if(injos[nod]<d)
        return 0;
    int cur=nod,auxd=d;
    while(cur!=root)
    {
        cur = parent[cur];
        auxd--;
        if(injos[cur]<auxd)
            return 0;
    }
    return 1;
}
int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);
    cin>>n>>d;
    int u;
    for(int i=2;i<=n;i++)
    {
        cin>>u;
        u++;
        con[i].push_back(u);
        con[u].push_back(i);
    }
    root=1;
    for(int i=1;i<=n;i++)
        if((int)con[i].size()>1)
            root=i;
    //cerr<<root<<" root\n";
    dfs(root);
    vector<pair<int,int>> v(n);
    for(int i=1;i<=n;i++)
    {
        v[i-1] = {-depth[i],i};
        injos[i] = d+5;
        //cerr<<i<<" "<<parent[i]<<" parent\n";
    }
    sort(v.begin(),v.end());
    int cnt=0;
    for(auto [_,i]:v)
    {
        if(verif(i))
        {
            injos[parent[i]] = 1;
            cnt++;
            //cerr<<i<<" ales\n";
        }
        else
        {
            injos[parent[i]] = min(injos[parent[i]], injos[i]+1);
        }
        if(i!=root)
        {
            int cur = parent[i];
            while(cur!=root)
            {
                injos[parent[cur]] = min(injos[parent[cur]], injos[cur]+1);
                cur = parent[cur];
            }
        }
    }
    cout<<cnt;
    return 0;
}

• Subtask 1: 11 / 11
• Subtask 2: 40 / 40
• Subtask 3: 0 / 49