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;
}