Submission #428359

#	Time	Username	Problem	Language	Result	Execution time	Memory
428359		oolimry	Cheerleaders (info1cup20_cheerleaders)	C++17	33 / 100	2075 ms	2392 KiB

cheerleaders

#include <bits/stdc++.h>
using namespace std;
#define sz(x) (int) (x).size()
#define all(x) (x).begin(), (x).end()
#define show(x) cerr << #x << " is " << x << endl;
#define show2(x,y) cerr << #x << " is " << x << " " << #y << " is " << y << endl;
#define show3(x,y,z) cerr << #x << " is " << x << " " << #y << " is " << y << " " << #z << " is " << z << endl;
#define tern(cond, a, b) (cond ? a : b)
typedef long long lint;
typedef pair<lint,lint> ii;

vector<int> original;
vector<int> arr;
vector<int> nxt;

lint ans = 123123231232132LL;
lint res = 0;

int main(){
	ios_base::sync_with_stdio(false); cin.tie(0);
	
	int n; cin >> n;
	int N = (1<<n);
	original.resize(N);
	for(int i = 0;i < N;i++) cin >> original[i];
	
	if(n == 0){
		cout << 0;
		return 0;
	}
	
	for(int iter = 0;iter < n;iter++){
		arr.clear();
		for(int i = 0;i < N;i++) arr.push_back(original[i]);
		
		res = 0;
		
		for(lint gap = (1<<(n-1));gap > 0;gap >>= 1){
			lint invcnt = 0;
			lint total = 0;
			for(int s = 0;s < N;s += 2*gap){
				int m = s+gap, e = s+2*gap;
				vector<int> R;
				for(int i = m;i < e;i++) R.push_back(arr[i]);
				sort(all(R));
				
				for(int i = s;i < m;i++){
					lint pos = lower_bound(all(R), arr[i]) - R.begin();
					invcnt += pos;
				}
				
				total += gap*gap;
			}
			
			//show2(invcnt, total-invcnt);
			if(total-invcnt < invcnt){
				res += total-invcnt;
			}
			else{
				res += invcnt;
			}
		}
		
		//show(res);
		ans = min(ans, res);
		
		//for(int i = 0;i < N;i++) cerr << arr[i] << " "; cerr << endl;
		
		nxt.clear();
		for(int i = 0;i < N;i += 2) nxt.push_back(original[i]);
		for(int i = 1;i < N;i += 2) nxt.push_back(original[i]);
		swap(nxt, original);
	}
	
	cout << ans;
}

• Subtask 1: 8 / 16
• Subtask 2: 5 / 10
• Subtask 3: 20 / 25
• Subtask 4: 0 / 21
• Subtask 5: 0 / 28