Cod sursa(job #984262)

Utilizator assa98Andrei Stanciu assa98 Data 13 august 2013 22:17:22
Problema Stramosi Scor 90
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.23 kb
#include <cstdio>
#include <algorithm>
#include <vector>
using namespace std;

struct Query {
    int p,num;

    Query() {
        p=num=0;
    }

    Query(int a,int b) {
        p=a;
        num=b;
    }
};


const int MAX_N = 500100;
const int MAX_M = 500100;


vector<int> A[MAX_N];

vector<Query> Q[MAX_N];

int sol[MAX_M];

int viz[MAX_N];

int n,m;

int st[MAX_N];

void bfs(int nod) {
    st[++st[0]]=nod;
    viz[nod]=1;


    for(vector<Query>::iterator it=Q[nod].begin(); it!= Q[nod].end(); it++) {
        if(it->p>=st[0])
            sol[it->num]=0;
        else
            sol[it->num]=st[st[0]-it->p];
    }
    
    for( vector<int>::iterator it=A[nod].begin(); it!= A[nod].end();it++) {
            bfs(*it);
    }

    st[0]--;
}

int main() {
    freopen("stramosi.in","r",stdin);
    freopen("stramosi.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1; i<=n; i++) {
        int a;
        scanf("%d",&a);
        if(a) {
            A[a].push_back(i);
        }
    }
    for(int i=1; i<=m; i++) {
        int p,q;
        scanf("%d%d",&q,&p);
        Q[q].push_back(Query(p,i));
    }
    
    for(int i=1;i<=n;i++)
        if(!viz[i])
            bfs(i);
    for(int i=1;i<=m;i++) 
        printf("%d\n",sol[i]);
    return 0;
}