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OI-codes/Luogu/P3391/P3391.cpp

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#include <iostream>
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#include <cstdlib>
using std::cin;
using std::cout;
#define endl '\n'
const int N = 1e5 + 5;
int n, m, l, r, root, cnt;
struct node {
int l, r, s, v, k;
bool d;
node()
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: l(0),
r(0),
s(0),
v(0),
d(false),
k(rand()) {}
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node(int _v)
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: l(0),
r(0),
s(1),
v(_v),
d(false),
k(rand()) {}
} tr[N];
void pushup(int u) {
tr[u].s = tr[tr[u].l].s + tr[tr[u].r].s + 1;
}
void pushdown(int u) {
if (tr[u].d) {
tr[u].d = false;
tr[tr[u].l].d ^= 1;
tr[tr[u].r].d ^= 1;
std::swap(tr[u].l, tr[u].r);
}
}
int build(int l, int r) {
if (l > r) return 0;
int mid = l + r >> 1;
int p = ++cnt;
tr[p] = node(mid - 1);
tr[p].l = build(l, mid - 1);
tr[p].r = build(mid + 1, r);
pushup(p);
return p;
}
std::pair<int, int> split(int p, int k) {
if (!p) return std::make_pair(0, 0);
pushdown(p);
if (k <= tr[tr[p].l].s) {
auto o = split(tr[p].l, k);
tr[p].l = o.second;
pushup(p);
o.second = p;
return o;
}
auto o = split(tr[p].r, k - tr[tr[p].l].s - 1);
tr[p].r = o.first;
pushup(p);
o.first = p;
return o;
}
int merge(int x, int y) {
if (!x || !y) return x | y;
pushdown(x);
pushdown(y);
if (tr[x].k > tr[y].k) {
tr[x].r = merge(tr[x].r, y);
pushup(x);
return x;
}
tr[y].l = merge(x, tr[y].l);
pushup(y);
return y;
}
void reserve(int l, int r) {
auto x = split(root, r + 1);
auto y = split(x.first, l);
tr[y.second].d ^= 1;
root = merge(merge(y.first, y.second), x.second);
}
void print(int p) {
if (!p) return;
pushdown(p);
print(tr[p].l);
if (1 <= tr[p].v && tr[p].v <= n) {
cout << tr[p].v << ' ';
}
print(tr[p].r);
}
int main() {
std::ios::sync_with_stdio(false);
cin >> n >> m;
root = build(1, n + 2);
while (m--) {
cin >> l >> r;
reserve(l, r);
}
print(root);
cout << endl;
return 0;
}