POJ 3264

RMQ模板题

#include <iostream>
#include <cstdio>
#include <string.h>
#include <cmath>
using namespace std;
const int N= 50002;
int maxn[N][17],minn[N][17];
int a[N];
int n,q;
void getRMQ(){
    for(int i=1;i<N;i++){maxn[i][0]=minn[i][0]=a[i];}
    for(int j=1;j<17;j++){
        for(int i=1;i<N;i++){
            if(i+(1<<j)<N){
                maxn[i][j]=max(maxn[i][j-1],maxn[i+(1<<(j-1))][j-1]);
                minn[i][j]=min(minn[i][j-1],minn[i+(1<<(j-1))][j-1]);
            }  
        }
    }
}
int rmq(int l,int r){
    int k=(int)(log((double)(r-l+1))/log(2.0));
    int Max=max(maxn[l][k],maxn[r-(1<<k)+1][k]);
    int Min=min(minn[l][k],minn[r-(1<<k)+1][k]);
    return Max-Min;
}
int main(){
    int l,r;
    scanf("%d%d",&n,&q);
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
    }
    getRMQ();
    while(q--){
        scanf("%d%d",&l,&r);
        printf("%d
",rmq(l,r));
    }
    return 0;
}