Cod sursa(job #1979692)

Utilizator RaresEGaySopterean Adrian RaresEGay Data 11 mai 2017 09:16:28
Problema Stramosi Scor 80
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.25 kb
#include <fstream>
#include <vector>
#include <stack>

#define maxn 250005
#define maxm 300005

using namespace std;

ifstream f ("stramosi.in");
ofstream g ("stramosi.out");

struct Query{
    int pos, father;
};

stack < int > root;
vector < Query > q[maxn];
vector < int > v[maxn];
vector < int > stiva;
int sol[maxm];

int n, m;

int DFS(int u){
    stiva.push_back(u);
    for(int i = 0; i < v[u].size(); ++i){
        if(!q[v[u][i]].empty()){
            for(int j = 0; j < q[v[u][i]].size(); ++j){
                if(q[v[u][i]][j].father <= stiva.size()){
                    sol[q[v[u][i]][j].pos] = stiva[stiva.size() - q[v[u][i]][j].father];
                }
            }
        }
        DFS(v[u][i]);
    }
    if(!stiva.empty())
        stiva.erase(stiva.begin() - 1 + stiva.size());
}

int main(){
    f >> n >> m;
    for(int i = 1; i <= n; ++i){
        int x;
        f >> x;
        if(x) v[x].push_back(i);
        else root.push(i);
    }
    for(int i = 1; i <= m; ++i){
        int vx, ft;
        f >> vx >> ft;
        q[vx].push_back((Query){i, ft});
    }
    while(!root.empty()){
        DFS(root.top());
        root.pop();
    }
    for(int i = 1; i <= m; ++i) g << sol[i] << '\n';
}