Submission #42665

#	Time	Username	Problem	Language	Result	Execution time	Memory
42665		XmtosX	Ball Machine (BOI13_ballmachine)	C++14	20.95 / 100	1087 ms	25612 KiB

ballmachine

#include <bits/stdc++.h>
using namespace std;
int n,minn[100005],root,q,sprs[100005][30],cnt[100005],pro[100005],cur,b;
vector <int> v[100005];
set <pair<int,int > > s;
bool yes[100005];
void dfs (int x,int p)
{
    minn[x]=x;
    if (p!=-1)
        sprs[x][0]=p;
    for (int i=1;i<30;i++)
        sprs[x][i]=sprs[sprs[x][i-1]][i-1];
    for (int i=0;i<v[x].size();i++)
    {
        if (v[x][i]!=p)
        {
            dfs(v[x][i],x);
            minn[x]=min(minn[x],minn[v[x][i]]);
            cnt[x]++;
        }
    }
}
void build (int x,int p)
{
    set <pair<int,int> > s1;
    for (int i=0;i<v[x].size();i++)
    {
        if (v[x][i]!=p)
        {
            s1.insert({minn[v[x][i]],v[x][i]});
        }
    }
    while (!s1.empty())
    {
        build(s1.begin()->second,x);
        s1.erase(s1.begin());
    }
    pro[x]=++cur;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >>n>>q;
    b=n;
    for (int i=1;i<=n;i++)
    {
        int a;
        cin >>a;
        if (!a)
            root=i;
        else
        {
            v[a].push_back(i);
            v[i].push_back(a);
        }
    }
    dfs (root,-1);
    for (int i=1;i<=n;i++)
    {
        if (!cnt[i])
        {
            s.insert({pro[i],i});
        }
    }
    while (q--)
    {
        int t,k;
        cin >>t>>k;
        if (t==1)
        {
            int x;
            while (k--&&b)
            {
                x= s.begin()->second;
                s.erase(s.begin());
                b--;
                yes[x]=true;
                if (x!=root)
                {
                    cnt[sprs[x][0]]--;
                    if (!cnt[sprs[x][0]])
                        s.insert({pro[sprs[x][0]],sprs[x][0]});
                }
            }
            cout <<x<<"\n";
        }
        else
        {
            int ans=0;
            for (int i=20;i>=0;i--)
            {
                if (yes[sprs[k][i]])
                {
                    k=sprs[k][i];
                    ans+= (1<<i);
                }
            }
            cout <<ans<<"\n";
            yes[k]=false;
            b++;
            s.insert({pro[k],k});
            if (k!=root)
            {
                if (!cnt[sprs[k][0]])
                    s.erase({pro[sprs[k][0]],sprs[k][0]});
                cnt[sprs[k][0]]++;
            }
        }
    }
    return 0;
}

Compilation message (stderr)

ballmachine.cpp: In function 'void dfs(int, int)':
ballmachine.cpp:14:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0;i<v[x].size();i++)
                   ^
ballmachine.cpp: In function 'void build(int, int)':
ballmachine.cpp:27:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0;i<v[x].size();i++)
                   ^
ballmachine.cpp: In function 'int main()':
ballmachine.cpp:88:20: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
             cout <<x<<"\n";
                    ^

• Subtask 1: 0 / 25
• Subtask 2: 10.714285714285714 / 30
• Subtask 3: 8.571428571428571 / 40
• Subtask 4: 1.6666666666666667 / 5