poj 3264

RMQ模版

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
int n,a[50010],q;
int dp1[50010][17],dp2[50010][17];
void RMQ_MIN(){
    int i,j;
    for(i=1;i<=n;i++)
        dp1[i][0]=a[i];
    for(j=1;j<=(int)(log((double)n)/log(2.0));j++)
        for(i=1;i+(1<<j)-1<=n;i++)
            dp1[i][j]=min(dp1[i][j-1],dp1[i+(1<<(j-1))][j-1]);
}

int query_min(int u,int v){
    int k=(int)((log((double)(v-u+1))/log(2.0)));
    return min(dp1[u][k],dp1[v-(1<<k)+1][k]);
}
void RMQ_MAX(){
    int i,j;
    for(i=1;i<=n;i++)
        dp2[i][0]=a[i];
    for(j=1;j<=(int)(log((double)n)/log(2.0));j++)
        for(i=1;i+(1<<j)-1<=n;i++)
            dp2[i][j]=max(dp2[i][j-1],dp2[i+(1<<(j-1))][j-1]);
}
int query_max(int u,int v){
    int k=(int)(log((double)(v-u+1))/log(2.0));
    return max(dp2[u][k],dp2[v-(1<<k)+1][k]);
}
int main(){
    int i,j,u,v;
    scanf("%d %d",&n,&q);
    for(i=1;i<=n;i++)
        scanf("%d",&a[i]);
    RMQ_MIN();
    RMQ_MAX();
    for(i=1;i<=q;i++){
        scanf("%d %d",&u,&v);
        printf("%d\n",query_max(u,v)-query_min(u,v));
    }
}