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,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;
}