求调,祝你rp++

#include<iostream>
#include<cmath>
#include<map>
#include<cstring>
#include<string>
#include<queue>
#include<algorithm>
#include<vector>
#include<stack>
using namespace std;
struct node{
	int ls,rs,sum,ms;
}tree[1000000];
int read(){
	int x = 0, f = 1;
	char c = getchar();
	while(c < '0' || c > '9'){
		if(c == '-'){
			f = -1;
		}
		c = getchar();
	}
	while(c >= '0' && c <= '9'){
		x = x*10+c-'0';
		c = getchar();
	}
	return x*f;
}
void down(int n){
	tree[n].sum=tree[n*2].sum+tree[n*2+1].sum;
	tree[n].ls=max(tree[n*2].ls,tree[n*2].sum+tree[n*2+1].ls);
	tree[n].rs=max(tree[n*2+1].rs,tree[n*2+1].sum+tree[n*2].rs);
	tree[n].ms=max(max(tree[n*2].ms,tree[n*2+1].ms),tree[n*2].rs+tree[n*2+1].ls);
}
void build(int l,int r,int n){
	if(l==r){
		cin >>tree[n].sum;
		tree[n].ls=tree[n].ms=tree[n].rs=tree[n].sum;
		return;
	}
	int mid=(l+r)/2;
	build(l,mid,n*2);
	build(mid+1,r,n*2+1);
	down(n);
}
node find(int l,int r,int n,int L,int R){
	if(L<=l&&r<=R){
		return tree[n];
	}
	int mid=(l+r)/2;
	node v;
	if(R<=mid)v=find(l,mid,n*2,L,R);
	else if(L>mid)v=find(mid+1,r,n*2+1,L,R);
	else{
		node v1,v2;
		v1=find(l,mid,n*2,L,R);
		v2=find(mid+1,r,n*2+1,L,R);
		v.sum=v1.sum+v2.sum;
		v.ls=max(v1.ls,v1.sum+v2.ls);
		v.rs=max(v2.rs,v2.sum+v1.rs);
		v.ms=max(max(v1.ms,v2.ms),v1.rs+v2.ls);
	}
	down(n);
	return v;
}
void gai(int l,int r,int n,int N,int v){
	if(l==r==N){
		tree[n].ls=tree[n].ms=tree[n].rs=tree[n].sum=v;
		return;
	}
	int mid=(l+r)/2;
	if(mid<=N)gai(l,mid,n*2,N,v);
	if(N>mid)gai(mid+1,r,n*2+1,N,v);
	down(n);
}
int n,m;
int main(){
	n=read();
	m=read();
	build(1,n,1);
	for(int i=1;i<=m;i++){
		int t=read(),l=read(),r=read();
		if(t==1){
			cout <<find(1,n,1,l,r).ms<<endl;
		}else{
			gai(1,n,1,l,r);
		}
	}
	return 0;
}