Cod sursa(job #988919)

Utilizator manutrutaEmanuel Truta manutruta Data 24 august 2013 12:10:20
Problema Stramosi Scor 90
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.06 kb
#include <cstdio>
#include <vector>
#include <bitset>
using namespace std;

#define MAXN 250005
#define BIT_MAX 32
typedef vector<int>::iterator iter;

vector<int> arb[MAXN];
int par[BIT_MAX][MAXN],stk[MAXN],sp=0,n,m;

void dfs(int nod){
    for(int i=1,cnt=0;cnt<BIT_MAX,i<=sp;i<<=1,cnt++){
        par[cnt][nod]=stk[sp-i];
    }
    stk[sp++]=nod;
    for(iter it=arb[nod].begin();it!=arb[nod].end();it++){
        dfs(*it);
    }
    sp--;
}

int query(int nod,int k){
    int lst=nod,b=0;
    do{
        if(k&1){
            lst=par[b][lst];
        }
        b++,k>>=1;
    }while(k && lst);
    return lst;
}

int main(){
    FILE* fin=fopen("stramosi.in","r");
    FILE* fout=fopen("stramosi.out","w");

    fscanf(fin,"%d %d\n",&n,&m);

    for(int i=1,t;i<=n;i++){
        fscanf(fin,"%d ",&t);
        arb[t].push_back(i);
    }

    dfs(0);

    for(int i=1,nod,k;i<=m;i++){
        fscanf(fin,"%d %d\n",&nod,&k);
        fprintf(fout,"%d\n",query(nod,k));
    }

    fclose(fin);
    fclose(fout);
    return 0;
}