Submission #1253059

#	Time	Username	Problem	Language	Result	Execution time	Memory
1253059		goulthen	Group Photo (JOI21_ho_t3)	C++20	0 / 100	0 ms	320 KiB

Main

//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T>
using Tree =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
 
#define int long long
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define rep(i, a, b) for (int i = a; i <= b; ++i)
#define per(i, b, a) for (int i = b; i >= a; --i)
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(), (v).end()
#define lsb(x) (x)&(-x)
#define bug(x) cerr << #x << " " << x << endl;
 
void setIO(string name = "") {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    if (!name.empty()) {
        freopen((name + ".in").c_str(), "r", stdin);
        freopen((name + ".out").c_str(), "w", stdout);
    }
}
 
ll fexp(ll a, ll b, ll m) {
    if (b == 0) return 1LL;
    ll p = a;
    ll ans = 1;
    while (b > 0) {
        if (b % 2 != 0) ans = (ans * p) % m;
        p = (p * p) % m;
        b >>= 1;
    }
    return ans;
}
 
const int MAXN = 5e3 + 10;
const int INF = 1e18 + 5;
const int MOD = 1e9+7;
int a[MAXN], dp[MAXN], inv[MAXN], bit[MAXN],n;

void update(int i, int x) {
    for (;i <= n; i += lsb(i)) bit[i] += x;
}

int query(int i) {
    int ans = 0;
    for (; i > 0; i -= lsb(i)) ans += bit[i];
    return ans;
}

void solve() {
    cin >> n;
    rep(i,1,n) {
        cin >> a[i];
        inv[a[i]] = i;
        update(i,1);
    }
    
    rep(i,1,n) {
        update(i,-1);
        dp[i] = INF;
        per(j,i,1) {
            update(j,1);
            int x = 0;
            rep(k,j,i) {   
                update(k,-1);
                x += query(inv[k]);
            }
            rep(k,j,i) update(k,1);
            dp[i] = min(dp[i], dp[j-1] + x);
        }
        per(j,i,1) update(j,-1);
    }


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

int32_t main() {
    setIO();
    int tt = 1;
    //cin >> tt;
 
    while (tt-- > 0) solve();
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'void setIO(std::string)':
Main.cpp:29:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |         freopen((name + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:30:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |         freopen((name + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 7
• Subtask 3: 0 / 32
• Subtask 4: 0 / 20
• Subtask 5: 0 / 36