Cod sursa(job #2534354)

Utilizator mihailescu_eduardMihailescu Eduard-Florin mihailescu_eduard Data 30 ianuarie 2020 14:48:34
Problema Stramosi Scor 80
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 2.15 kb
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")

#include <bits/stdc++.h>

using namespace std;

#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
  enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "


// CHECK THE LIMITS
typedef long long ll;

const int MOD = 1000000007;
const ll INFLL = 1e18;
const int INF = 1e9;
const int NMAX = 250005;

int gcd(int a, int b) {
  return b ? gcd(b, a%b) : a;
} 

ifstream fin("stramosi.in");
ofstream fout("stramosi.out");

// 2^18 > NMAX
int stramosi[NMAX][19];
int tata[NMAX];
int solve(int x, int y)
{
    int cur = 1;
    vector<int> sol;
    while(y)
    {
        if(y&1)
        {
            sol.push_back(cur);
        }
        y>>=1;
        cur++;
    } 
    int n = (int) sol.size();
    int res = stramosi[x][sol[n-1]];

    for(int i = n-2; i>=0 && res;i--)
    {
        res = stramosi[res][sol[i]];
    }
    return res;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n,m;
    fin >> n >> m;
    for(int i  =1; i<= n; ++i)
    {
        fin >> tata[i];
    }

    // construct matrix;
    for(int i = 1; i<=n; ++i)
    {
        stramosi[i][1] = tata[i];
        int k = 1;
        int nxt = tata[i];
        while(stramosi[nxt][k])
        {
            stramosi[i][k+1] = stramosi[nxt][k];
            nxt = stramosi[nxt][k];
            k++;
        }

    }

    for(int i = 1; i<= m; ++i)
    {
        int x,y;
        fin>> x >> y;
        fout << solve(x,y) << '\n';
    }

    return 0;
}