线段树模板

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
#define LL(x) (x<<1)
#define RR(x) (x<<1|1)
#define MID(a,b) (a+((b-a)>>2))
#define INF (1<<30)
const int N=200005;
struct node
{
    int lft,rht,mx,mi,sum;
    int mid()
    {
        return MID(lft,rht);
    }
};
int y[N],n,m;
struct Segtree
{
    node tree[N*4];
    void build(int lft,int rht,int ind )
    {
        tree[ind].lft=lft;
        tree[ind].rht=rht;
        tree[ind].mx=-INF;
        tree[ind].mi=INF;
        tree[ind].sum=0;
        if(lft==rht)
        {
            tree[ind].mi=y[lft];
            tree[ind].mx=y[lft];
            tree[ind].sum=y[lft];
        }
        else
        {
            int mid=tree[ind].mid();
            build(lft,mid,LL(ind));
            build(mid+1,rht,RR(ind));
            tree[ind].mx=max(tree[LL(ind)].mx,tree[RR(ind)].mx);
            tree[ind].mi=min(tree[LL(ind)].mi,tree[RR(ind)].mi);
            tree[ind].sum=tree[LL(ind)].sum+tree[RR(ind)].sum;
        }


    }
    void updata(int pos,int ind,int valu)
    {
        int lft=tree[ind].lft,rht=tree[ind].rht;
        if(lft==rht)
        {
            tree[ind].mx=valu;
            tree[ind].sum=valu;
            tree[ind].mi=valu;
        }
        else
        {
            int mid=tree[ind].mid();
            if(pos<=mid)updata(pos,LL(ind),valu);
            else updata(pos,RR(ind),valu);
            tree[ind].mx=max(tree[LL(ind)].mx,tree[RR(ind)].mx);
            tree[ind].mi=min(tree[LL(ind)].mi,tree[RR(ind)].mi);
            tree[ind].sum=tree[LL(ind)].sum+tree[RR(ind)].sum;


        }
    }
    int querymx(int st,int ed,int ind)
    {
        int lft=tree[ind].lft,rht=tree[ind].rht;
        if(st<=lft&&rht<=ed)return tree[ind].mx;
        else
        {
            int mid=tree[ind].mid();
            int mx1=-INF,mx2=-INF;
            if(st<=mid)mx1=querymx(st,ed,LL(ind));
            if(ed>mid)mx2=querymx(st,ed,RR(ind));
            return max(mx1,mx2);
        }


    }
    int querymi(int st,int ed,int ind)
    {
        int lft=tree[ind].lft,rht=tree[ind].rht;
        if(st<=lft&&rht<=ed)return tree[ind].mi;
        else
        {
            int mid=tree[ind].mid();
            int mi1=INF,mi2=INF;
            if(st<=mid)mi1=querymi(st,ed,LL(ind));
            if(ed>mid)mi2=querymi(st,ed,RR(ind));
            return min(mi1,mi2);
        }


    }
    int querysum(int st,int ed,int ind)
    {
        int lft=tree[ind].lft,rht=tree[ind].rht;
        if(st<=lft&&rht<=ed)return tree[ind].sum;
        else
        {
            int mid=tree[ind].mid();
            int sum1=0,sum2=0;
            if(st<=mid)sum1=querysum(st,ed,LL(ind));
            if(ed>mid)sum2=querysum(st,ed,RR(ind));
            return sum1+sum2;
        }


    }


} seg;


int main()
{


    int n,m;
    while(cin>>n>>m)
    {
        for(int i=1; i<=n; i++)
            cin>>y[i];
        seg.build(1,n,1);
        char s;
        int st,ed;
        for(int i=0; i<m; i++)
        {
            cin>>s>>st>>ed;


            if(s=='S')cout<<seg.querysum(st,ed,1)<<endl;
            if(s=='A')cout<<seg.querymx(st,ed,1)<<endl;
            if(s=='I')cout<<seg.querymi(st,ed,1)<<endl;


        }


    }


    return 0;
}