线段树20pts求条

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+5;
struct node 
{
	int sum;
	int l;
	int r;
	bool lzy;
};
node tr[N*4];
int a[N];
void pushup(int u)
{
	tr[u].sum=tr[u*2].sum+tr[u*2+1].sum;
}

void pushdown(int u)
{
	if(tr[u].lzy)
	{
		tr[u].lzy=0;
		tr[u*2].lzy=1;
		tr[u*2].sum=tr[u*2].r-tr[u*2].l+1-tr[u*2].sum;
		tr[u*2+1].lzy=1;
		tr[u*2+1].sum=tr[u*2+1].r-tr[u*2+1].l+1-tr[u*2+1].sum;
	}
}

void bui(int u,int l,int r)
{
	tr[u].l=l;tr[u].r=r;tr[u].lzy=0;tr[u].sum=0;
	if(l==r)
		return ;
	int mid=(l+r)/2;
	if(l<=mid)
		bui(u*2,l,mid);
	if(r>mid)
		bui(u*2+1,mid+1,r);
	pushup(u);
}
int query(int u,int l,int r)
{
	if(tr[u].l>=l&&tr[u].r<=r)
		return tr[u].sum;
	pushdown(u);
	int mid=(tr[u].l+tr[u].r)/2;
	int sum=0;
	if(l<=mid)
		sum+=query(u*2,l,r);
	if(r>mid)
		sum+=query(u*2+1,l,r);
	return sum;
}
void modify(int u,int l,int r)
{
	if(tr[u].l>=l&&tr[u].r<=r)
	{
		tr[u].sum=tr[u].r-tr[u].l+1-tr[u].sum;
		tr[u].lzy=1;
	}
	else
	{
		pushdown(u);
		int mid=(tr[u].l+tr[u].r)/2;
		if(l<=mid)
			modify(u*2,l,r);
		if(r>mid)
			modify(u*2+1,l,r);
		pushup(u);
	}
}
int main()
{
	int n,m;
	cin>>n>>m;
	bui(1,1,n);
	while(m--)
	{
		int c,a,b;
		cin>>c>>a>>b;
		if(c==0)
		{
			modify(1,a,b);
		}
		else
		{
			cout<<query(1,a,b)<<endl;			
		}
	}
	return 0;
}