mirror of
https://git.sb/baoshuo/OI-codes.git
synced 2024-11-08 14:18:47 +00:00
351B - Jeff and Furik
https://codeforces.com/problemset/submission/351/173713009
This commit is contained in:
parent
6d2b982d60
commit
fc18c9b0b0
43
Codeforces/351/B/B.cpp
Normal file
43
Codeforces/351/B/B.cpp
Normal file
@ -0,0 +1,43 @@
|
||||
#include <iostream>
|
||||
|
||||
using std::cin;
|
||||
using std::cout;
|
||||
const char endl = '\n';
|
||||
|
||||
const int N = 3005;
|
||||
|
||||
int n, p[N], c[N], ans;
|
||||
|
||||
int lowbit(int x) {
|
||||
return x & -x;
|
||||
}
|
||||
|
||||
void add(int x, int y) {
|
||||
for (; x <= n; x += lowbit(x)) c[x] += y;
|
||||
}
|
||||
|
||||
int sum(int x) {
|
||||
int res = 0;
|
||||
for (; x; x -= lowbit(x)) res += c[x];
|
||||
return res;
|
||||
}
|
||||
|
||||
int main() {
|
||||
std::ios::sync_with_stdio(false);
|
||||
cin.tie(nullptr);
|
||||
|
||||
cin >> n;
|
||||
|
||||
for (int i = 1; i <= n; i++) {
|
||||
cin >> p[i];
|
||||
}
|
||||
|
||||
for (int i = n; i; i--) {
|
||||
ans += sum(p[i] - 1);
|
||||
add(p[i], 1);
|
||||
}
|
||||
|
||||
cout << (ans * 2 - ans % 2) << endl;
|
||||
|
||||
return 0;
|
||||
}
|
Loading…
Reference in New Issue
Block a user