SPOJ GSS3 Can you answer these queries III[线段树]

Input

Output

Example

Input:
4
1234
4
113
03-3
124
133

Output:
6
4
-3

GSS1加个单点修改

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#definem((l+r)>>1)
#definelsono<<1,l,m
#definersono<<1|1,m+1,r
#definelco<<1
#definerco<<1|1
usingnamespacestd;
typedeflonglongll;
constintN=5e5+5,INF=2e9+5;
inlineintread(){
charc=getchar();intx=0,f=1;
while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
returnx*f;
}
intn,q,op,x,y;
structnode{
intsum,mx,pre,suf;
}t[N<<2];
voidmerge(into){
t[o].sum=t[lc].sum+t[rc].sum;
t[o].mx=max(t[lc].suf+t[rc].pre,max(t[lc].mx,t[rc].mx));
t[o].pre=max(t[lc].pre,t[lc].sum+t[rc].pre);
t[o].suf=max(t[rc].suf,t[rc].sum+t[lc].suf);
}
voidbuild(into,intl,intr){
if(l==r)t[o].sum=t[o].mx=t[o].pre=t[o].suf=read();
else{
build(lson);
build(rson);
merge(o);
}
}
intqpre(into,intl,intr,intql,intqr){
if(ql<=l&&r<=qr)returnt[o].pre;
elseif(qr<=m)returnqpre(lson,ql,qr);
elsereturnmax(qpre(lson,ql,qr),t[lc].sum+qpre(rson,ql,qr));
}
intqsuf(into,intl,intr,intql,intqr){
if(ql<=l&&r<=qr)returnt[o].suf;
elseif(m<ql)returnqsuf(rson,ql,qr);
elsereturnmax(t[rc].suf,t[rc].sum+qsuf(lson,ql,qr));
}
intqmx(into,intl,intr,intql,intqr){
if(ql<=l&&r<=qr)returnt[o].mx;
else{
intans=-INF;
if(ql<=m)ans=max(ans,qmx(lson,ql,qr));
if(m<qr)ans=max(ans,qmx(rson,ql,qr));
if(ql<=m&&m<qr)ans=max(ans,qsuf(lson,ql,qr)+qpre(rson,ql,qr));
returnans;
}
}
voidupdate(into,intl,intr,intp,intv){
if(l==r)t[o].sum=t[o].mx=t[o].pre=t[o].suf=v;
else{
if(p<=m)update(lson,p,v);
elseupdate(rson,p,v);
merge(o);
}
}
intmain(){
n=read();
build(1,1,n);
q=read();
for(inti=1;i<=q;i++){
op=read();x=read();y=read();
if(op)printf("%d\n",qmx(1,1,n,x,y));
elseupdate(1,1,n,x,y);
}
}