Cod sursa(job #2197841)

Utilizator emanuel_rRamneantu Emanuel emanuel_r Data 22 aprilie 2018 22:34:00
Problema Range minimum query Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 2.41 kb
#include <bits/stdc++.h>

using namespace std;

template <typename ForwardIterator, typename Function>
class RMQ{
public:
    ForwardIterator first, last;
    using T = typename iterator_traits<ForwardIterator>::value_type;
    vector<T> V;                //value
    vector<vector<T> > M;       //index of the largest/smallest value
    Function func;
    vector<int> L; //logs
    int n = 0;

    RMQ(ForwardIterator a, ForwardIterator b, Function f) : first(a), last(b), func(f) {};

    void build(){
        while(first!=last){
            V.emplace_back(*first);
            first++;
            n++;
        }

        M.resize(n);

        for(int i = 0; i < n; i++)
            M[i].emplace_back(i);

        L.emplace_back(0);
        L.emplace_back(0);
        for(int i = 2; i <= n; i++)
            L.emplace_back(L[i/2] + 1);

        for(int step = 1; step <= L[n]; step++){
            for(int i = 0; i < n - (1<<step) + 1; i++)
                M[i][step] = func(V[ M[i][step - 1] ], V[ M[i + (1<<(step - 1))][step - 1] ]) ?
                             M[i][step - 1] : M[i + (1<<(step - 1))][step - 1];
        }
    }

    int iQuery(int begin, int end){
        int step = L[end - begin + 1];
        if(func(V[ M[begin][step] ], V[ M[end - (1<<step) + 1][step] ] ))
            return M[begin][step];
        return M[end - (1<<step) + 1][step];
    }

    T vQuery(int begin, int end){
        return V[iQuery(begin, end)];
    }
};

int n, m;
vector<int> V;
RMQ<vector<int>::iterator, function<bool(int, int)> > *R;

void Read()
{
    scanf("%d %d", &n, &m);
    int x;
    for(int i = 0; i < n; i++) {
        scanf("%d", &x);
        V.emplace_back(x);
    }
}

void Solve()
{
    int a, b;
    //clock_t t = clock();
    R->build();
    //t = clock() - t;
    //cerr<<(double)t/CLOCKS_PER_SEC<<"\n";
    for(int i = 0; i < m; i++){
        scanf("%d %d", &a, &b);
        printf("%d\n", R->vQuery(a - 1, b - 1) );
    }
}

int main()
{
    //ios_base::sync_with_stdio(false);
    freopen("rmq.in", "r", stdin);
    freopen("rmq.out", "w", stdout);
    //clock_t t = clock();
    Read();
    R = new RMQ<vector<int>::iterator, function<bool(int, int)> >
            (V.begin(), V.end(), [](int a, int b) -> bool { return a < b; });
    Solve();
    //t = clock() - t;
    //cerr<<(double)t/CLOCKS_PER_SEC<<"\n";
    //delete R;
    return 0;
}