poj 3264

来源：互联网发布：python 汉字编码转换编辑：程序博客网时间：2024/04/29 10:02

思路：线段树求区间最大最小值

#include <iostream>#include <stdio.h>#include <cstring>#define MAXN 300000using namespace std;typedef long long ll;ll a[MAXN];struct note{    int rr,ll;    long long mm,nn;}q[MAXN*3];void build(int i,int l,int r){    q[i].rr=r;    q[i].ll=l;    if(l==r)    {        q[i].mm=q[i].nn=a[l];        return ;    }    int m=(l+r)/2;    build(i*2,l,m);    build(i*2+1,m+1,r);    q[i].mm=max(q[i*2].mm,q[i*2+1].mm);    q[i].nn=min(q[i*2].nn,q[i*2+1].nn);}ll query1(int i,int l,int r){    if(l<=q[i].ll&&r>=q[i].rr)    {        return q[i].mm;    }    int m=(q[i].ll+q[i].rr)/2;    if(r<=m)        return query1(i*2,l,r);    else if(l>m)        return query1(i*2+1,l,r);    else        return max(query1(i*2,l,r),query1(i*2+1,l,r));}ll query2(int i,int l,int r){    if(l<=q[i].ll&&r>=q[i].rr)    {        return q[i].nn;    }    int m=(q[i].ll+q[i].rr)/2;    if(r<=m)        return query2(i*2,l,r);    else if(l>m)        return query2(i*2+1,l,r);    else        return min(query2(i*2,l,r),query2(i*2+1,l,r));}int main(){   // freopen("in.txt","r",stdin);    int n,m;    while(scanf("%d%d",&n,&m)!=EOF)    {        for(int i=1;i<=n;i++)            scanf("%lld",&a[i]);        build(1,1,n);        int x,y;        for(int i=0;i<m;i++)        {            scanf("%d%d",&x,&y);            printf("%lld\n",query1(1,x,y)-query2(1,x,y));        }    }}

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