poj 3264 RMQ

#include <iostream>#include <cstdio>#include <cstring>#include <cmath>using namespace std;const int maxn=5e4+9;int maxrmq[maxn][20],minrmq[maxn][20],a[maxn];int n,q;void getrmq(){    for(int i=1;i<=n;i++)    minrmq[i][0]=maxrmq[i][0]=a[i];    for(int i=1;(1<<i)<=n;i++)    for(int j=1;j+(1<<i)-1<=n;j++)    {        maxrmq[j][i]=max(maxrmq[j][i-1],maxrmq[j+(1<<i-1)][i-1]);        minrmq[j][i]=min(minrmq[j][i-1],minrmq[j+(1<<i-1)][i-1]);    }}int askrmq(int t,int s){    int k=log(s-t+1)/log(2);    int mmax=max(maxrmq[t][k],maxrmq[s-(1<<k)+1][k]);    int mmin=min(minrmq[t][k],minrmq[s-(1<<k)+1][k]);    return mmax-mmin;}int main(){//    freopen("in.txt","r",stdin);    while(scanf("%d %d",&n,&q)!=EOF)    {        for(int i=1;i<=n;i++)        scanf("%d",&a[i]);        getrmq();        for(int i=1,t,s;i<=q;i++)        {            scanf("%d %d",&t,&s);            printf("%d\n",askrmq(t,s));        }    }    return 0;}