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OI-codes/AcWing/241/241.cpp

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#include <iostream>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 2e5 + 5;
int n, y[N], l[N], r[N], c1[N], c2[N];
long long ans1, ans2;
inline int lowbit(int x) {
return x & -x;
}
void add(int *c, int x, int y) {
for (; x <= n; x += lowbit(x)) c[x] += y;
}
int sum(int *c, int x) {
int ans = 0;
for (; x; x -= lowbit(x)) ans += c[x];
return ans;
}
int main() {
std::ios::sync_with_stdio(false);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> y[i];
}
for (int i = 1; i <= n; i++) {
l[i] = sum(c1, y[i] - 1);
add(c1, y[i], 1);
}
for (int i = n; i; i--) {
r[i] = sum(c2, y[i] - 1);
add(c2, y[i], 1);
}
for (int i = 1; i <= n; i++) {
ans1 += 1ll * (i - 1 - l[i]) * (n - i - r[i]);
ans2 += 1ll * l[i] * r[i];
}
cout << ans1 << ' ' << ans2 << endl;
return 0;
}