Cod sursa(job #2490980)

Utilizator ViAlexVisan Alexandru ViAlex Data 11 noiembrie 2019 16:22:48
Problema Range minimum query Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.32 kb
#include<bits/stdc++.h>
using namespace std;

ifstream in("rmq.in");
ofstream out("rmq.out");

int values[100000],n,m;
int lookup[100000][21];
int logx2[20];



void read()
{
    in>>n>>m;
    for(int i=0; i<n; i++)
        in>>values[i];
}

void logarithm_table()
{
    logx2[0]=1;
    for(int i=1; i<=20; i++)
    {
        logx2[i]=2*logx2[i-1];
    }

}

void create_lookup()
{
    for(int i=0; 1<<i <=n; i++)
    {
        int pp=1<<i,last=1<<(i-1);

        for(int k=0; k<=n-pp; k++)
        {
            if(i==0)
            {
                lookup[k][i]=values[k];
            }
            else
            {
                lookup[k][i]=min(lookup[k][i-1],lookup[k+last][i-1]);
            }

        }
    }
}



int get_minimum_interval(int a,int b)
{
    int result=9999999;

    int index=20;
    while(index>=0)
    {
        if(logx2[index]<=(b-a))
        {
            result=min(result,lookup[a][index]);
            a+=logx2[index];
        }
        if(a==b)
        {
            result=min(result,values[a]);
            break;
        }

        index--;
    }
    return result;

}

void solve()
{
    int a,b;
    for(int i=0; i<m; i++)
    {
        in>>a>>b;
        out<<get_minimum_interval(a-1,b-1)<<'\n';
    }

}

int main()
{
    logarithm_table();
    read();
    create_lookup();
    solve();
    return 0;

}