求助QAQ

萌新线段树只有9分(A了第一个点)，看了看之前的讨论也没有发现类似的错误

#include<cstdio>
#include<cstring>
#include<algorithm>
#define int long long
using namespace std;
int n,m,sum,cnt;
int num[100100];
struct node{
    int l,r,sum,lm,rm,maxn;
}tree[4000100];
void pushup(int id)
{
    if(tree[id*2].rm<0&&tree[id*2+1].lm<0)tree[id].maxn=(tree[id*2].rm,tree[id*2+1].lm);
    else
    {
        tree[id].maxn=0;
        if(tree[id*2].rm>0)tree[id].maxn+=tree[id*2].rm;
        if(tree[id*2+1].lm>0)tree[id].maxn+=tree[id*2+1].lm;
    }
    tree[id].maxn=max(tree[id].maxn,max(tree[id*2].maxn,tree[id*2+1].maxn));    
    tree[id].lm=max(tree[id*2].lm,tree[id*2].sum+tree[id*2+1].lm);
    tree[id].rm=max(tree[id*2+1].rm,tree[id*2].rm+tree[id*2+1].sum);
    tree[id].sum=tree[id*2].sum+tree[id*2+1].sum;   
}
void build(int id,int l,int r)
{
    tree[id].l=l;tree[id].r=r;tree[id].maxn=0;
    if(l==r)
    {
        tree[id].lm=tree[id].rm=tree[id].maxn=tree[id].sum=num[l];
        return;
    }
    int mid=(l+r)/2;
    build(id*2,l,mid);
    build(id*2+1,mid+1,r);
    pushup(id);
}
void add(int id,int p,int k)
{
    if(tree[id].l==tree[id].r&&tree[id].l==p)
    {
        tree[id].lm=tree[id].rm=tree[id].maxn=tree[id].sum=k;
        return;
    }
    int mid=(tree[id].l+tree[id].r)/2;
    if(p<=mid)add(id*2,p,k);
    if(p>mid)add(id*2+1,p,k);
    pushup(id);
}
int find(int id,int l,int r)
{
    if(l<=tree[id].l&&tree[id].r<=r)return tree[id].maxn;
    int mid=(tree[id].l+tree[id].r)/2;
    int ans=-0x3f3f3f3f;
    if(l<=mid)ans=max(ans,find(id*2,l,r));
    if(r>mid)ans=max(ans,find(id*2+1,l,r));
    return ans;
}
signed main()
{
    scanf("%lld%lld",&n,&m);
    for(int i=1;i<=n;++i)scanf("%lld",&num[i]);
    build(1,1,n);
    for(int i=1;i<=m;++i)
    {
        int x,y,z;
        scanf("%lld",&z);
        if(z==1)
        {
            scanf("%lld%lld",&x,&y);
            if(x>y)swap(x,y);
            printf("%lld\n",find(1,x,y));
        }
        else
        {
            scanf("%lld%lld",&x,&y);
            add(1,x,y);
        }
    }
    return 0;
}