Codeforces - Physical Education Lessons

题目链接：Codeforces - Physical Education Lessons

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做法很多，离散化线段树，动态开点线段树，ODT，Splay。

这四种都是随便维护一下就行了。

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AC代码：

#pragma GCC optimize("-Ofast","-funroll-all-loops")
#include<bits/stdc++.h>
//#define int long long
using namespace std;
const int N=3e5+10,M=N*50;
int n,q,rt=1,sum[M],lc[M],rc[M],lazy[M],cnt=1;
char *fs,*ft,buf[1<<20];
#define gc() (fs==ft&&(ft=(fs=buf)+fread(buf,1,1<<20,stdin),fs==ft))?0:*fs++;
inline int read(){
    int x=0,f=1; char ch=gc();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=gc();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=gc();}
    return x*f;
}
inline void push_up(int p){sum[p]=sum[lc[p]]+sum[rc[p]];}
inline void push_down(int p,int l,int r){
	if(lazy[p]==-1)	return ;	int mid=l+r>>1;
	lazy[lc[p]]=lazy[rc[p]]=lazy[p];
	sum[lc[p]]=(mid-l+1)*lazy[p];
	sum[rc[p]]=(r-mid)*lazy[p];
	lazy[p]=-1;
}
void change(int p,int l,int r,int ql,int qr,int k){
	if(l==ql&&r==qr){sum[p]=(r-l+1)*k; lazy[p]=k; return ;}	
	if(!lc[p]&&!rc[p])	lc[p]=++cnt,lazy[cnt]=-1,rc[p]=++cnt,lazy[cnt]=-1;
	int mid=l+r>>1;	push_down(p,l,r);
	if(qr<=mid)	change(lc[p],l,mid,ql,qr,k);
	else if(ql>mid)	change(rc[p],mid+1,r,ql,qr,k);
	else change(lc[p],l,mid,ql,mid,k),change(rc[p],mid+1,r,mid+1,qr,k);
	push_up(p);
}
signed main(){
	n=read(),q=read();	lazy[1]=-1;
	for(int i=1,l,r,k;i<=q;i++){
		l=read(),r=read(),k=read();	change(rt,1,n,l,r,(k==1?1:0));
		printf("%d\n",n-sum[rt]);
	}
	return 0;
}