Cod sursa(job #2602279)

Utilizator As932Stanciu Andreea As932 Data 16 aprilie 2020 15:34:23
Problema Range minimum query Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.04 kb
#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("rmq.in");
ofstream fout("rmq.out");

const int nmax=100005;

int n,m,a[nmax],sparse[nmax][20],log2[nmax];

void read()
{
    fin>>n>>m;

    for(int i=0;i<n;i++)
    {
        fin>>a[i];
        sparse[i][0]=i;
    }
}

void preLog2()
{
    log2[1]=0;
    for(int i=2;i<nmax;i++)
        log2[i]=1+log2[i/2];
}

void preSparse()
{
    for(int j=1;(1<<j)<=n;j++)
        for(int i=0;i+(1<<j)-1<n;i++)
            if(a[sparse[i][j-1]]<a[sparse[i+(1<<(j-1))][j-1]])
                sparse[i][j]=sparse[i][j-1];
            else
                sparse[i][j]=sparse[i+(1<<(j-1))][j-1];
}

int rmq(int x,int y)
{
    int len=y-x+1;
    int k=log2[len];

    return min(a[sparse[x][k]],a[sparse[x+len-(1<<k)][k]]);
}

void query()
{
    for(int i=1;i<=m;i++)
    {
        int x,y;
        fin>>x>>y;
        fout<<rmq(x-1,y-1)<<"\n";
    }
}

int main()
{
    read();
    preLog2();
    preSparse();
    query();

    return 0;
}