Submission #499858

#	Time	Username	Problem	Language	Result	Execution time	Memory
499858		Lobo	Group Photo (JOI21_ho_t3)	C++17	100 / 100	703 ms	200616 KiB

Main

#include<bits/stdc++.h>
using namespace std;
 
/*for ordered_set
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<pair<int,int>, null_type,less<pair<int,int>>, rb_tree_tag,tree_order_statistics_node_update>
*/
 
const long long INFll = (long long) 1e18 + 10;
const int INFii = (int) 1e9 + 10;
typedef long long ll;
typedef int ii;
typedef long double dbl;
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
 
#define maxn 5100
 
ii n, a[maxn], pos[maxn], dp[maxn], mark[maxn];
ii bit[maxn][maxn], bit1[maxn][maxn];
 
void att(ii id1, ii id2, ii val) {
    for(ii i = id2; i <= n; i+= i&-i) {
        bit[id1][i]+= val;
    }
}
 
ii qr(ii id1, ii id2) {
    ii val = 0;
    for(ii i = id2; i > 0; i-= i&-i) {
        val+= bit[id1][i];
    }
    return val;
}

void att1(ii id1, ii id2, ii val) {
    for(ii i = id2; i <= n; i+= i&-i) {
        bit1[id1][i]+= val;
    }
}
 
ii qr1(ii id1, ii id2) {
    ii val = 0;
    for(ii i = id2; i > 0; i-= i&-i) {
        val+= bit1[id1][i];
    }
    return val;
}
 
ii sol(ii i) {
    if(mark[i]) return dp[i];
    mark[i] = 1;
    ii ans = INFii;
    if(i == n) return dp[i] = 0;

    for(ii j = 1; j <= n; j++) {
        bit[i][j] = 0;
        bit1[i][j] = 0;
    }

    for(ii j = 1; j <= i; j++) {
        att(i,pos[j],1);
    }

    ii ans1 = 0;
    for(ii j = i+1; j <= n; j++) {
        //colocando o j com os <= i
        ans1+= i-qr(i,pos[j]);

        //atualizando a parte do j -> j+1
        ans1+= j-i-1;

        //colocando a mudanca pos[x] > pos[j]
        ans1-= j-i-1-qr1(i,pos[j]);
        att1(i,pos[j],1);

        ans = min(ans, ans1+sol(j));

        // cout << i << " " << j << " " << ans1 << " " << sol(j) << endl;
    }
 
    return dp[i] = ans;
}
 
void solve() {
    cin >> n;
 
    for(ii i = 1; i <= n; i++) {
        cin >> a[i];
        pos[a[i]] = i;
    }
 
    cout << sol(0) << endl;
 
    
}
 
int main() {
    ios::sync_with_stdio(false); cin.tie(0);
 
    // freopen("in.in", "r", stdin);
    //freopen("out.out", "w", stdout);
 
    ii tt = 1;
    // cin >> tt;
    while(tt--) solve();
 
}

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