RT，开了double，该pushdown也pushdown了，还是 WA 0

#include<cstdio>
using namespace std;
int n,m;
double num[100010],tree_1[400010],tree_2[400010],lazy_1[400010],lazy_2[400010];
void build_sum(int now,int l,int r)
{
	if(l==r)
	{
		tree_1[now]=num[l];
		return;
	}
	int mid=(l+r)>>1;
	build_sum(now<<1,l,mid);
	build_sum(now<<1|1,mid+1,r);
	tree_1[now]=tree_1[now<<1]+tree_1[now<<1|1];
}
void build_sqr_sum(int now,int l,int r)
{
	if(l==r)
	{
		tree_2[now]=num[l]*num[l];
		return;
	}
	int mid=(l+r)>>1;
	build_sqr_sum(now<<1,l,mid);
	build_sqr_sum(now<<1|1,mid+1,r);
	tree_2[now]=tree_2[now<<1]+tree_2[now<<1|1];
}
void push_down(int now,int l,int r)
{
	int mid=(l+r)>>1;
	tree_2[now<<1]+=2*lazy_2[now]*tree_1[now<<1]+(mid-l+1)*lazy_2[now]*lazy_2[now];
	tree_2[now<<1|1]+=2*lazy_2[now]*tree_1[now<<1|1]+(r-mid)*lazy_2[now]*lazy_2[now];
	tree_1[now<<1]+=lazy_1[now]*(mid-l+1);
	tree_1[now<<1|1]+=lazy_1[now]*(r-mid);
	lazy_2[now<<1]+=lazy_2[now];
	lazy_2[now<<1|1]+=lazy_2[now];
	lazy_1[now<<1]+=lazy_1[now];
	lazy_1[now<<1|1]+=lazy_1[now];
	lazy_2[now]=0;
	lazy_1[now]=0;
}
void change(int now,int l,int r,int x,int y,int k)
{
	if(r<x||l>y) return;
	if(x<=l&&r<=y)
	{
		lazy_2[now]+=k;
		tree_2[now]+=2*k*tree_1[now]+(r-l+1)*k*k;
		lazy_1[now]+=k;
		tree_1[now]+=k*(r-l+1);
		return;
	}
	if(lazy_1[now]||lazy_2[now]) push_down(now,l,r);
	int mid=(l+r)>>1;
	if(x<=mid) change(now<<1,l,mid,x,y,k);
	if(y>mid) change(now<<1|1,mid+1,r,x,y,k);
	tree_1[now]=tree_1[now<<1]+tree_1[now<<1|1];
	tree_2[now]=tree_2[now<<1]+tree_2[now<<1|1];
}
double find_1(int now,int l,int r,int x,int y)
{
	if(r<x||l>y) return 0;
	if(x<=l&&r<=y) return tree_1[now];
	if(lazy_1[now]) push_down(now,l,r);
	int mid=(l+r)>>1;
	double result=0;
	if(x<=mid) result+=find_1(now<<1,l,mid,x,y);
	if(y>mid) result+=find_1(now<<1|1,mid+1,r,x,y);
	return result;
}
double find_2(int now,int l,int r,int x,int y)
{
	if(r<x||l>y) return 0;
	if(x<=l&&r<=y) return tree_2[now];
	if(lazy_2[now]) push_down(now,l,r);
	int mid=(l+r)>>1;
	double result=0;
	if(x<=mid) result+=find_2(now<<1,l,mid,x,y);
	if(y>mid) result+=find_2(now<<1|1,mid+1,r,x,y);
	return result;
}
int main()
{
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)
		scanf("%lf",&num[i]);
	build_sum(1,1,n);
	build_sqr_sum(1,1,n);
	for(int i=1;i<=m;i++)
	{
		int opt,x,y;
		double z;
		scanf("%d%d%d",&opt,&x,&y);
		if(opt==1)
		{
			scanf("%lf",&z);
			change(1,1,n,x,y,z);
		}
		else if(opt==2)
			printf("%.4lf\n",find_1(1,1,n,x,y)/(y-x+1));
		else
		{
			double result=0,avr;
			avr=find_1(1,1,n,x,y)/(y-x+1);
			result-=avr*avr;
			result+=find_2(1,1,n,x,y)/(y-x+1);
			printf("%.4lf\n",result);
		}
	}
}