Cod sursa(job #773788)

Utilizator veleanduAlex Velea veleandu Data 2 august 2012 16:32:28
Problema Stramosi Scor 80
Compilator cpp Status done
Runda Arhiva de probleme Marime 2.46 kb
// rezolvare off-line

#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

    typedef struct { long a,b,nro,rez; } query;
    query Q[300005];
    long i,n,m,x;
    long Nr[300005],nr,act;
    long Nr2[300005],nr2;
    long C[300005];
    vector <long> V[300005];

    void DFs ( long varf )
    {
        nr2=1;
        while ( nr2>0 )
        {
            //printf ("%d %d\n",varf,nr);
            if ( !C[varf] )
            {
                Nr[varf]=nr;
                nr++;
            }
            if ( C[varf] == (V[varf].size() ))
            // trecem inapoi
            {
                nr2--;
                varf=Nr2[nr2];
            }
            else{
                // mai bagam pe cineva in parcurgere

                nr2++;
                Nr2[nr2]=V[varf][C[varf]];
                C[varf]++;
                varf=Nr2[nr2];
            }
        }
    }
    bool mysort ( query a, query b )
    {
        return Nr[a.b]<Nr[b.b];
    }
    bool mysort2 ( query a, query b )
    {
        return a.nro<b.nro;
    }
    void DFs_2 ( long varf )
    {

        nr2=1;
        while ( nr2>0 )
        {
            if ( !C[varf] )
            {

                while ( Q[act].b == varf && varf!=0)
                {

                    if ( Q[act].a > nr2 )
                        Q[act].rez=0;
                    else
                        Q[act].rez=Nr2[nr2-Q[act].a];
                    act++;
                }
            }
            if ( C[varf] == (V[varf].size() ))
            // trecem inapoi
            {
                nr2--;
                varf=Nr2[nr2];
            }
            else{
                // mai bagam pe cineva in parcurgere

                nr2++;
                Nr2[nr2]=V[varf][C[varf]];
                C[varf]++;
                varf=Nr2[nr2];
            }
        }
    }



int main()
{
    freopen ("stramosi.in","r",stdin);
    freopen ("stramosi.out","w",stdout);
    cin>>n>>m;
    for ( i=1; i<=n; i++ )
    {
        cin>>x;
        V[x].push_back(i);
    }
    for ( i=1; i<=m; i++ )
    {
        cin>>Q[i].b>>Q[i].a;
        Q[i].nro=i;
    }
    DFs(0);
    sort ( Q+1, Q+m+1, mysort );
    nr=0;
    act=1;
    Nr[0]=0;
    for ( i=0; i<=n; i++ )
        C[i]=0;
    DFs_2(0);
    sort ( Q+1, Q+m+1, mysort2 );

    for ( i=1; i<=m; i++ )
        printf ("%d\n",Q[i].rez);
}