Cod sursa(job #1162916)

Utilizator misu007Pogonaru Mihai misu007 Data 1 aprilie 2014 01:13:19
Problema Range minimum query Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.36 kb
#include <cstdio>
#include <algorithm>
using namespace std;

const int dim=100001;

int n,m,a[dim],lg[dim],rmq[dim][18]; //2^18>dim

//in rmq tinem pozitia minimului din sirul initial si nu minimul propriuzis. poate ajuta la unele probleme pentru reducerea memoriei
//cand e nevoie de pozitia din sirul initial. ex: lca

void read()
{
    freopen("rmq.in","r",stdin);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;++i) scanf("%d",&a[i]);
}

void rmqf()
{
    int i,k;
    for(i=2;i<=n;++i)
    {
        lg[i]=lg[i>>1]+1;
    }
    for(i=1;i<=n;++i)
    {
        rmq[i][0]=i;
    }
    for(k=1;(1<<k)<=n;++k)
    {
        for(i=1;i<=n-(1<<k)+1;++i)
        {
            if(a[rmq[i][k-1]]<a[rmq[i+(1<<(k-1))][k-1]])
            {
                rmq[i][k]=rmq[i][k-1];
            }
            else
            {
                rmq[i][k]=rmq[i+(1<<(k-1))][k-1];
            }
        }
    }
}

int main()
{
    read();
    rmqf();
    freopen("rmq.out","w",stdout);
    int x,y,diff;
    while(m)
    {
        --m;
        scanf("%d%d",&x,&y);
        diff=y-x+1;
        if(a[rmq[x][lg[diff]]]<a[rmq[y-(1<<lg[diff])+1][lg[diff]]])
        {
            printf("%d\n",a[rmq[x][lg[diff]]]);
        }
        else
        {
            printf("%d\n",a[rmq[y-(1<<lg[diff])+1][lg[diff]]]);
        }
    }
    return 0;
}