Codeforces 915E-Physical Education Lessons

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本文介绍了一道关于计算学期末剩余工作日数量的问题。通过使用动态线段树及懒惰标记的方法，有效地解决了更新区间内工作日状态的挑战。

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This year Alex has finished school, and now he is a first-year student of Berland State University. For him it was a total surprise that even though he studies programming, he still has to attend physical education lessons. The end of the term is very soon, but, unfortunately, Alex still hasn't attended a single lesson!

Since Alex doesn't want to get expelled, he wants to know the number of working days left until the end of the term, so he can attend physical education lessons during these days. But in BSU calculating the number of working days is a complicated matter:

There are n days left before the end of the term (numbered from 1 to n), and initially all of them are working days. Then the university staff sequentially publishes q orders, one after another. Each order is characterised by three numbers l, r and k:

If k = 1, then all days from l to r (inclusive) become non-working days. If some of these days are made working days by some previous order, then these days still become non-working days;
If k = 2, then all days from l to r (inclusive) become working days. If some of these days are made non-working days by some previous order, then these days still become working days.

Help Alex to determine the number of working days left after each order!

Input

The first line contains one integer n, and the second line — one integer q (1 ≤ n ≤ 109, 1 ≤ q ≤ 3·105) — the number of days left before the end of the term, and the number of orders, respectively.

Then q lines follow, i-th line containing three integers li, ri and ki representing i-th order (1 ≤ li ≤ ri ≤ n, 1 ≤ ki ≤ 2).

Output

Print q integers. i-th of them must be equal to the number of working days left until the end of the term after the first i orders are published.

Example

input
4
6
1 2 1
3 4 1
2 3 2
1 3 2
2 4 1
1 4 2

output
2
0
2
3
1
4

题意：有n 天（一开始都是工作日），之后会发布q个通知，通知的格式为：l r k。如果k=1，就说明从第l天到第r天都变成非工作日；如果k=2，就说明从第l天到第r天都变成工作日，每次输出有多少个工作日。

解题思路：动态建线段树再加上个lazy标记即可

#include <iostream>    
#include <cstdio>    
#include <cstring>    
#include <string>    
#include <algorithm>    
#include <map>    
#include <set>    
#include <stack>    
#include <queue>    
#include <vector>    
#include <bitset>    
#include <functional>    

using namespace std;

#define LL long long    
const int INF = 0x3f3f3f3f;

int n, L[15000009], R[15000009], sum[15000009], lazy[15000009];
int q, l, r, k, cnt;

void Pushdown(int k, int l, int r)
{
	if (!L[k])
	{
		L[k] = cnt++;
		L[L[k]] = R[L[k]] = 0;
	}
	if (!R[k])
	{
		R[k] = cnt++;
		L[R[k]] = R[R[k]] = 0;
	}
	lazy[L[k]] = lazy[R[k]] = lazy[k];
	sum[L[k]] = lazy[k] * ((l + r) / 2 - l + 1);
	sum[R[k]] = lazy[k] * (r - (l + r) / 2);
	lazy[k] = -1;
}

void update(int &k, int l, int r, int ll, int rr, int val)
{
	if (!k)
	{
		k = cnt++;
		L[k] = R[k] = 0;
		sum[k] = r - l + 1;
		lazy[k] = -1;
	}
	if (l >= ll && r <= rr)
	{
		sum[k] = (r - l + 1) * val;
		lazy[k] = val;
		return;
	}
	if (lazy[k] != -1) Pushdown(k, l, r);
	int mid = (l + r) >> 1;
	if (ll <= mid) update(L[k], l, mid, ll, rr, val);
	if (rr > mid) update(R[k], mid + 1, r, ll, rr, val);
	sum[k] = (L[k] ? sum[L[k]] : ((r + l) / 2 - l + 1)) + (R[k] ? sum[R[k]] : (r - (r + l) / 2));
}

int main()
{
	while (~scanf("%d", &n))
	{
		L[1] = R[1] = L[0] = R[0] = 0;
		sum[1] = n, lazy[1] =  -1, cnt = 2;
		int root = 1;
		scanf("%d", &q);
		while (q--)
		{
			scanf("%d%d%d", &l, &r, &k);
			if (n == 1)
			{
				if (k == 1) printf("0\n");
				else printf("1\n");
				continue;
			}
			update(root, 1, n, l, r, k == 2);
			printf("%d\n", sum[root]);
		}
	}
	return 0;
}