P3870 [TJOI2009] 开关（线段树）

P3870 [TJOI2009] 开关

思路：可以用线段树来维护区间中亮灯的个数，区间修改用加上懒标记就好

#include <bits/stdc++.h>
#define LL long long
using namespace std;

const int N = 1e5 + 10;

struct SegmentTree{
	int l, r;
	LL sum, add;
	#define l(x) tree[x].l
	#define r(x) tree[x].r
	#define sum(x) tree[x].sum
	#define add(x) tree[x].add
}tree[4 * N];
int n, m;

void build(int p, int l, int r)
{
	l(p) = l, r(p) = r;
	if(l == r)	{sum(p) = 0; return;}
	int mid = (l + r) >> 1;
	build(p << 1, l, mid);
	build(p << 1 | 1, mid + 1, r);
	sum(p) = sum(p << 1) + sum(p << 1 | 1);
}

//懒标记下传
void spread(int p)
{
	//节点p
	if(add(p))
	{
		sum(p << 1) = r(p << 1) - l(p << 1) + 1 - sum(p<<1);//更新左子节点信息
		sum(p << 1 | 1) = r(p << 1 | 1) - l(p << 1 | 1) + 1 - sum(p << 1 | 1);//更新右子节点信息
		add(p << 1) = ~add(p << 1);//给左子节点打延迟标记
		add(p << 1 | 1) = ~add(p << 1 | 1);//给右子节点打延迟标记
		add(p) = 0;	//清楚p的标记
	}
}

void change(int p, int l, int r)
{
	if(l <= l(p) && r >= r(p))
	{
		sum(p) = r(p) - l(p) + 1 - sum(p);
		add(p) = ~add(p);
		return;
	}
	spread(p);
	int mid = (l(p) + r(p)) >> 1;
	if(l <= mid) change(p << 1, l, r);
	if(r > mid)	change(p << 1 | 1, l, r);
	sum(p) = sum(p << 1) + sum(p << 1 | 1);
}

long long ask(int p, int l, int r)
{
	if(l <= l(p) && r >= r(p))	return sum(p);
	spread(p);
	int mid = (l(p) + r(p)) >> 1;
	long long val = 0;
	if(l <= mid) val += ask(p << 1, l , r);
	if(r > mid) val += ask(p << 1 | 1, l, r);
	return val;
}

void solve()
{

	cin >> n >> m;
	build(1, 1, n);

	while(m --)
	{
		int op, l, r, d;
		cin >> op >> l >> r;
		if(op == 0)	change(1, l, r);
		else	cout << ask(1, l, r) << endl;
	}
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
//	freopen("1.in", "r", stdin);
	solve();
	return 0;
}