还有3天AFO了，调不动了，救救孩子吧[大哭]

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#define ll long long
using namespace std;
const int maxn=1e6+10;
const ll INF=4557430888798830399;
int n,m;
ll a[maxn],sum[4*maxn],lzy_tag[4*maxn],lzy_tag2[4*maxn],maxx[4*maxn];
//lzy_tag1[]是"加上x"的标记数组; lzy_tag2[]是"修改为x"的标记数组 
void build(int l,int r,int p)	//p是当前的节点
{
	if(l==r){
		maxx[p]=a[l];
		sum[p]=a[l];
		return;
	}
	int mid=(l+r)>>1;
	build(l,mid,2*p);
	build(mid+1,r,2*p+1);
	sum[p]=sum[p*2]+sum[p*2+1];
	maxx[p]=max(maxx[2*p],maxx[2*p+1]);
}
void push_down_lzy_tag(int l,int r,int p)
{
	int mid=(l+r)>>1;
	sum[p*2]+=lzy_tag[p]*(mid-l+1);
	sum[p*2+1]+=lzy_tag[p]*(r-mid);
	maxx[p*2]+=lzy_tag[p];
	maxx[p*2+1]+=lzy_tag[p];
	lzy_tag[p*2]+=lzy_tag[p];
	lzy_tag[p*2+1]+=lzy_tag[p];
	lzy_tag[p]=0;
}
void push_down_lzy_tag2(int l,int r,int p)
{
	int mid=(l+r)>>1;
	sum[p*2]=lzy_tag2[p]*(mid-l+1);
	sum[p*2+1]=lzy_tag2[p]*(r-mid);
	maxx[p*2]=lzy_tag2[p];
	maxx[p*2+1]=lzy_tag2[p];
	lzy_tag2[p*2]=lzy_tag2[p];
	lzy_tag2[p*2+1]=lzy_tag2[p];
	lzy_tag2[p]=0;
}
ll getmax(int l,int r,int L,int R,int p)	//[L,R]是要查询的区间
{
	if(L<=l&&r<=R) return maxx[p];
	int mid=(l+r)>>1;
	ll maxxx=-INF;
	if(lzy_tag2[p]!=INF)
	{
		push_down_lzy_tag2(l,r,p);
	}
	if(lzy_tag[p])
	{
		push_down_lzy_tag(l,r,p);
	}
	if(L<=mid) maxxx=max(maxxx,getmax(l,mid,L,R,p*2));
	if(R>mid) maxxx=max(maxxx,getmax(mid+1,r,L,R,p*2+1));
	return maxxx;
}
void update(int l,int r,int L,int R,int p,int f)
{
	if(L<=l&&r<=R)
	{
		sum[p]+=(r-l+1)*f;
		maxx[p]+=f;
		lzy_tag[p]+=f;
		return;
	}
	if(lzy_tag2[p]!=INF)
	{
		push_down_lzy_tag2(l,r,p);
	}
	if(lzy_tag[p])
	{
		push_down_lzy_tag(l,r,p);
	}
	int mid=(l+r)>>1;
	if(L<=mid) update(l,mid,L,R,p*2,f);
	if(R>mid) update(mid+1,r,L,R,p*2+1,f);
	sum[p]=sum[p*2]+sum[p*2+1];
	maxx[p]=max(maxx[2*p],maxx[2*p+1]);
}
void update2(int l,int r,int L,int R,int p,int f)
{
	if(L<=l&&r<=R){
		sum[p]=(r-l+1)*f;
		maxx[p]=f;
		lzy_tag2[p]=f;
		return;
	}
	if(lzy_tag2[p]!=INF)
	{
		push_down_lzy_tag2(l,r,p);
	}
	if(lzy_tag[p])
	{
		push_down_lzy_tag(l,r,p);
	}
	int mid=(l+r)>>1;
	if(L<=mid) update2(l,mid,L,R,p*2,f);
	if(R>mid) update2(mid+1,r,L,R,p*2+1,f);
	sum[p]=sum[p*2]+sum[p*2+1];
	maxx[p]=max(maxx[2*p],maxx[2*p+1]);
}
int main()
{
	scanf("%d%d",&n,&m);
	memset(maxx,-0x3f,sizeof(maxx));
	memset(lzy_tag2,0x3f,sizeof(lzy_tag2));
	for(int i=1;i<=n;i++)	scanf("%lld",&a[i]);
	build(1,n,1);
	for(int i=1;i<=m;i++)
	{
		int op,x,y;
		scanf("%d%d%d",&op,&x,&y);
		if(op==1)
		{
			int k;
			scanf("%d",&k);
			update2(1,n,x,y,1,k);
		}
		else if(op==2){
			int k;
			scanf("%d",&k);
			update(1,n,x,y,1,k);
		}
		else if(op==3){
			printf("%lld\n",getmax(1,n,x,y,1));
		}
	}
	return 0;
}

WA on #7~10