CF915E Physical Education Lessons 动态开点线段树

题目链接

CF915E Physical Education Lessons

题解

动态开点线段树

代码

/*
动态开点线段树 
*/
#include<cstdio> 
#include<cstring> 
#include<algorithm> 

inline int read() { 
	int x = 0,f = 1; 
	char c  = getchar() ; 
	while(c < '0' || c > '9')c = getchar(); 
	while(c <= '9' && c >= '0') x = x * 10 + c - '0',c = getchar(); 
	return x * f; 
} 
const int maxn = 500007 * 30; 
int rt = 0; 
struct Segtree { 
	int tot ; 
	int ls[maxn],rs[maxn],tag[maxn],sum[maxn]; 
	void pushdown(int x,int l,int r) { 
		int mid = l + r >> 1;  
		if(l != r) { 
 			if(!ls[x]) ls[x] = ++ tot; //记得开点这里 
 			if(!rs[x]) rs[x] = ++ tot; 
			sum[ls[x]] = (mid - l + 1) * tag[x]; 
			sum[rs[x]] = (r - mid) * tag[x]; 
			tag[ls[x]] = tag[x]; 
			tag[rs[x]] = tag[x]; 
		} 
		tag[x] = -1; 
	} 
	void modify(int &x,int l,int r,int L,int R,int w) {
		if(!x) x = ++ tot; 
		if(l >= L && r <= R) { 
			sum[x] = (r - l + 1) * w; 
			tag[x] = w; 
			return; 
		} 
		if(tag[x] >= 0) pushdown(x,l,r); 
		int mid = l + r >> 1; 
		if(L <= mid) modify(ls[x],l,mid,L,R,w); 
		if(R >  mid) modify(rs[x],mid + 1,r,L,R,w); 
		sum[x] = sum[ls[x]] + sum[rs[x]]; 
	} 
} t; 
int main() { 
	int n = read(); 
	int m = read(); 
	memset(t.tag,-1,sizeof t.tag); 
	for(int type,l,r,i = 1;i <= m;++ i) { 
		l = read(),r = read(),type = read(); 
		if(type == 1) t.modify(rt,1,n,l,r,1); 
		else t.modify(rt,1,n,l,r,0); 
		printf("%d\n",n - t.sum[1]); 
	} 
	return 0; 
}