#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using max_heap = priority_queue<T, vector<T>, less<T>>;
using int64 = long long;
using ld = long double;
constexpr int kInf = 1e9 + 10;
constexpr int64 kInf64 = 1e15 + 10;
constexpr int kMod = 1e9 + 7;
template<class node, class F = std::function<node(const node &, const node &)>>
class SegTree {
int n = 0;
std::vector<node> t;
F unite;
void build(const int x, const int l, const int r, const std::vector<node> &a) {
if (l == r) {
t[x] = a[l];
return;
}
const int mid = (l + r) / 2;
const int y = 2 * (mid - l + 1) + x;
build(x + 1, l, mid, a);
build(y, mid + 1, r, a);
t[x] = unite(t[x + 1], t[y]);
}
void update(const int x, const int l, const int r, const int p, const node &v) {
if (l == p and p == r) {
t[x] = v;
return;
}
const int mid = (l + r) / 2;
const int y = 2 * (mid - l + 1) + x;
if (p <= mid) {
update(x + 1, l, mid, p, v);
} else {
update(y, mid + 1, r, p, v);
}
t[x] = unite(t[x + 1], t[y]);
}
node query(const int x, const int l, const int r, const int ql, const int qr) const {
if (ql <= l and r <= qr) {
return t[x];
}
const int mid = (l + r) / 2;
const int y = 2 * (mid - l + 1) + x;
if (qr <= mid) {
return query(x + 1, l, mid, ql, qr);
} else if (mid < ql) {
return query(y, mid + 1, r, ql, qr);
} else {
return unite(query(x + 1, l, mid, ql, qr), query(y, mid + 1, r, ql, qr));
}
}
void debug_node(const int x, const vector<int> &path) const {
for (int i = 0; i < path.size(); i++) {
cerr << path[i] << (i == path.size() - 1 ? ": " : " -> ");
}
cerr << t[x] << '\n';
}
void debug(const int x, const int l, const int r, vector<int> path) const {
path.push_back(x);
if (l == r) {
debug_node(x, path);
return;
}
const int mid = (l + r) / 2;
const int y = 2 * (mid - l + 1) + x;
debug(x + 1, l, mid, path);
debug(y, mid + 1, r, path);
debug_node(x, path);
}
public:
SegTree() = default;
explicit SegTree(const int n, const node e, F f) : n(n), t(2 * n - 1, e), unite(std::move(f)) {}
explicit SegTree(const std::vector<node> &a, F f) : n(a.size()), t(2 * (a.size()) - 1), unite(std::move(f)) {
build(0, 0, n - 1, a);
}
void set(const int p, const node &v) {
assert(0 <= p and p < n);
update(0, 0, n - 1, p, v);
}
[[nodiscard]] node get(const int l, const int r) const {
assert(0 <= l and l <= r and r < n);
return query(0, 0, n - 1, l, r);
}
void debug() const {
debug(0, 0, n - 1, {});
cerr << "----------\n\n";
}
};
int64 count_swaps(std::vector<int> S) {
const int shoes = S.size();
const int n = shoes / 2;
vector<vector<int>> occ(shoes + 1);
auto get = [&](const int i) -> vector<int> & {
return occ[i + n];
};
vector<int> final(shoes);
vector<int> seen(n + 1);
for (int i = 0, j = 0; i < shoes; i++) {
get(S[i]).push_back(i);
const int shoe = abs(S[i]);
seen[shoe] += (S[i] < 0 ? -1 : 1);
if (max(seen[shoe], S[i]) >= 0 and min(seen[shoe], S[i]) <= 0) continue;
final[j] = -shoe;
final[j + 1] = shoe;
j += 2;
}
for (vector<int> &v : occ) {
sort(v.rbegin(), v.rend());
}
SegTree<int> st(shoes, 0, [](const int a, const int b) {
return a + b;
});
for (int i = 0; i < shoes; i++) {
st.set(i, 1);
}
int64 swaps = 0;
for (int i = 0; i < shoes; i++) {
const int idx = get(final[i]).back();
get(final[i]).pop_back();
st.set(idx, 0);
swaps += st.get(0, idx);
}
return swaps;
}
