P3870 [TJOI2009] 开关

P3870 [TJOI2009] 开关

TJOI2009] 开关 - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

线段树

维护区间和，区间异或

区间异或可视为 区间和 = 区间长度 - 区间和

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <cmath>

using namespace std;
typedef long long ll;
const int N = 1e5 + 10;
int n, m;
struct Node
{
	int l, r;
	int sum, lazy;
}tr[N*4];
void pushup(int u)
{
	tr[u].sum = tr[u << 1].sum + tr[u << 1 | 1].sum;
}
void pushdown(int u)
{
	Node &root = tr[u], &left = tr[u << 1], &right = tr[u << 1 | 1];
	if (root.lazy)
	{
		left.sum = left.r - left.l + 1 - left.sum;
		right.sum = right.r - right.l + 1 - right.sum;
		left.lazy ^= 1;
		right.lazy ^= 1;
		root.lazy = 0;
	}
}

void build(int u, int l, int r)
{
	if (l == r)
	{
		tr[u] = {l, r, 0, 0};
		return;
	}
	tr[u] = {l, r};
	int mid = l + r >> 1;
	build(u << 1, l, mid);
	build(u << 1 | 1, mid + 1, r);
	pushup(u);
}

void modify(int u, int l, int r)
{
	if (tr[u].l >= l && tr[u].r <= r)
	{
		tr[u].lazy ^= 1;
		tr[u].sum = tr[u].r - tr[u].l + 1 - tr[u].sum;
		return;
	}
	int mid = tr[u].l + tr[u].r >> 1;
	pushdown(u);
	if (l <= mid)
		modify(u << 1, l, r);
	if (r > mid)
		modify(u << 1 | 1, l, r);
	pushup(u);
}

int query(int u, int l, int r)
{
	if (tr[u].l >= l && tr[u].r <= r)
	{
		return tr[u].sum;
	}
	int mid = tr[u].l + tr[u].r >> 1;
	pushdown(u);
	int ans = 0;
	if (l <= mid)
		ans = query(u << 1, l, r);
	if (r > mid)
		ans += query(u << 1 | 1, l, r);
	pushup(u);
	return ans;
}
int main()
{
	ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	cin >> n >> m;
	build(1, 1, n);
	while(m--)
	{
		int c, a, b;
		cin >> c >> a >> b;
		if (c == 0)
			modify(1, a, b);
		else
			cout << query(1, a, b) << endl;
	}
	return 0;
}