Submission #709982

#	Time	Username	Problem	Language	Result	Execution time	Memory
709982		nicky4321	Group Photo (JOI21_ho_t3)	C++14	100 / 100	1761 ms	67512 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pdd pair<double, double>
#define ALL(x) x.begin(), x.end()
#define vi vector<int>
#define vl vector<ll>
#define SZ(x) (int)x.size()
#define CASE int t;cin>>t;for(int ca=1;ca<=t;ca++)
#define IOS ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
const int MAX = 5007, MOD = 1e9 + 7;
int a[MAX], ans[MAX], dp[MAX][MAX], id[MAX];
int bit[MAX][5];

void upd(int x, int v, int ty){
    while(x < MAX){
        bit[x][ty] += v;
        x += x & -x;
    }
}

int qry(int x, int ty){
    int res = 0;
    while(x){
        res += bit[x][ty];
        x -= x & -x;
    }
    return res;
}

void solve(){
    int n;
    cin >> n;
    for(int i = 1;i <= n;i++){
        cin >> a[i];
        ans[i] = 2e9;
        id[a[i]] = i;
    }
    for(int i = 1;i <= n;i++){
        int now = 0;
        for(int j = n;j >= 1;j--){
            if(i <= a[j]){
                int pos = i + n - a[j];
                now += qry(pos, 0);
                upd(pos, 1, 0);
                upd(j, 1, 1);
            }
        }
        for(int j = n;j >= i;j--){
            dp[i][j] = now;
            upd(id[j], -1, 1);
            now += j - i - qry(id[j], 1);
            now -= qry(id[j], 1);
            now -= qry(id[j], 2);
            upd(id[j], 1, 2);
        }
        for(int j = n;j >= 1;j--){
            if(i <= a[j]){
                int pos = i + n - a[j];
                upd(pos, -1, 0);
            }
        }
        for(int j = n;j >= i;j--)
            upd(id[j], -1, 2);
    }
    for(int i = 0;i < n;i++){
        for(int j = i + 1;j <= n;j++){
            ans[j] = min(ans[j], ans[i] + dp[i + 1][j]);
        }
    }
    cout << ans[n] << '\n';
}

int main(){
    IOS
    // CASE
        solve();
    return 0;
}

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