Submission #773322

#	Time	Username	Problem	Language	Result	Execution time	Memory
773322		raysh07	Group Photo (JOI21_ho_t3)	C++17	100 / 100	901 ms	196580 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF (int)1e18
#define f first
#define s second

mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());

const int N = 5005;
int m, f[N][2];

void upd(int x, int j, int v = 1){
	for (int i = x; i <= m; i += i & (-i))
		f[i][j] += v;
}

int query(int x, int j){
	int res = 0;
	for (int i = x; i; i -= i & (-i))
		res += f[i][j];
	return res;
}

void Solve()
{
	int n; cin >> n;
	m = n;
	vector <int> a(n + 1), b(n + 1);
	for (int i = 1; i <= n; i++){
		cin >> a[i]; b[a[i]] = i;
	}

	vector<vector<int>> c(n + 1, vector<int>(n + 1));

	for (int i = 1; i <= n; i++){
		for (int i = 1; i <= m; i++) f[i][0] = f[i][1] = 0;

		int val = 0;
		for (int j = i; j >= 1; j--){
			upd(b[j], 0);
		}
		for (int j = i; j >= 1; j--){
			val += query(m, 0) - query(b[j], 0);
			val -= query(b[j], 1);
		//	upd(b[j], 0, -1);
			upd(b[j], 1);

			c[j][i] = val;

		//	cout << j << " " << i << " " << val << "\n";
		}
	}

	vector <int> dp(n + 1, INF);
	dp[0] = 0;
	for (int i = 1; i <= n; i++){
		for (int j = 0; j < i; j++){
			dp[i] = min(dp[i], dp[j] + c[j + 1][i]);
		}
	}

	cout << dp[n] << "\n";
}

int32_t main() 
{
    auto begin = std::chrono::high_resolution_clock::now();
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
 //    freopen("in",  "r", stdin);
	// freopen("out", "w", stdout);
  //  cin >> t;
    for(int i = 1; i <= t; i++) 
    {
        //cout << "Case #" << i << ": ";
        Solve();
    }
    auto end = std::chrono::high_resolution_clock::now();
    auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
    cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n"; 
    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 20 / 20
• Subtask 5: 36 / 36