[HEOI2016/TJOI2016]排序

https://www.luogu.com.cn/problem/P2824

题解：仔细思考可以发现这道题与https://arc101.contest.atcoder.jp/tasks/arc101_b?lang=en 是等价的。二分之后原问题就转化为了$0,1$序列,可以直接用线段树维护。

#include<iostream>
using namespace std;
struct node
{
	int l,r,data,lazy;
};
struct reads
{
	int op,l,r;
};
node tree[1000001];
reads q[1000001];
int a[1000001],p[1000001],n,m,Q;
void build(int k,int l,int r)
{
	tree[k].l=l;
	tree[k].r=r;
	tree[k].lazy=-1;
	int mid=(l+r)/2;
	if (l==r)
	{
		tree[k].data=p[l];
		return;
	}
	build(k*2,l,mid);
	build(k*2+1,mid+1,r);
	tree[k].data=tree[k*2].data+tree[k*2+1].data;
	return;
}
void spread(int k)
{
	if (tree[k].lazy==0)
	{
		tree[k].lazy=-1;
		tree[k*2].lazy=tree[k*2+1].lazy=tree[k*2].data=tree[k*2+1].data=0;
		return;
	}
	if (tree[k].lazy==1)
	{
		tree[k].lazy=-1;
		tree[k*2].data=tree[k*2].r-tree[k*2].l+1;
		tree[k*2+1].data=tree[k*2+1].r-tree[k*2+1].l+1;
		tree[k*2].lazy=tree[k*2+1].lazy=1;
		return;
	}
	return;
}
void add(int k,int l,int r,int d)
{
	if (l>r)
		return;
	if (tree[k].l==l&&tree[k].r==r)
	{
		tree[k].data=d*(tree[k].r-tree[k].l+1);
		tree[k].lazy=d;
		return;
	}
	spread(k);
	int mid=(tree[k].l+tree[k].r)/2;
	if (l<=mid&&r<=mid)
	{
		add(k*2,l,r,d);
		tree[k].data=tree[k*2].data+tree[k*2+1].data;
		return;
	}
	if (l>=mid+1&&r>=mid+1)
	{
		add(k*2+1,l,r,d);
		tree[k].data=tree[k*2].data+tree[k*2+1].data;
		return;
	}
	add(k*2,l,mid,d);
	add(k*2+1,mid+1,r,d);
	tree[k].data=tree[k*2].data+tree[k*2+1].data;
	return;
}
int sum(int k,int l,int r)
{
	if (tree[k].l==l&&tree[k].r==r)
		return tree[k].data;
	spread(k);
	int mid=(tree[k].l+tree[k].r)/2;
	if (l<=mid&&r<=mid)
		return sum(k*2,l,r);
	if (l>=mid+1&&r>=mid+1)
		return sum(k*2+1,l,r);
	return sum(k*2,l,mid)+sum(k*2+1,mid+1,r);
}
bool msort(int S)
{
	int res;
	for (int i=1;i<=n;++i)
		p[i]=(a[i]>=S);
	build(1,1,n);
	for (int i=1;i<=m;++i)
	{
		res=sum(1,q[i].l,q[i].r);
		if (q[i].op==0)
		{
			add(1,q[i].l,q[i].r-res,0);
			add(1,q[i].r-res+1,q[i].r,1);
		}
		else
		{
			add(1,q[i].l,q[i].l+res-1,1);
			add(1,q[i].l+res,q[i].r,0);
		}
	} 
	return sum(1,Q,Q);
}
int main()
{
	cin>>n>>m;
	for (int i=1;i<=n;++i)
		cin>>a[i];
	for (int i=1;i<=m;++i)
		cin>>q[i].op>>q[i].l>>q[i].r;
	cin>>Q;
	int first=1,last=n,mid,ans=1;
	while (first<=last)
	{
		mid=(first+last)/2;
		if (msort(mid))
		{
			ans=max(ans,mid);
			first=mid+1;
		}
		else
			last=mid-1;
	}
	cout<<ans<<endl;
	return 0;
}