Submission #1273903

#	Time	Username	Problem	Language	Result	Execution time	Memory
1273903		olizarowskib	Group Photo (JOI21_ho_t3)	C++20	100 / 100	587 ms	464620 KiB

Main

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ft first
#define sc second
#define pb push_back
#define all(x) x.begin(), x.end()
#define pi pair<int, int>
#define vi vector<int>
#define tii tuple<int, int, int>
#define tiii tuple<int, int, int, int>
#define tiiii tuple<int, int, int, int, int>
#define vpi vector<pi>
#define vtii vector<tii>
#define vtiii vector<tiii>

const int N = 5009, MOD = 1e9 + 7, INF = int(1e9);

int ile[N][N];
int p[N], poz[N];

void count_ile(int n){
    for(int i = 1; i <= n; i++){
        for(int j = i - 1; j > 0; j--){
            ile[i][j] = ile[i][j + 1] + (poz[j] < poz[i]);
        }
    }
}

int inw[N][N];

void count_inw(int n){
    for(int i = 1; i <= n; i++){
        for(int j = i + 1; j <= n; j++){
            inw[i][j] = inw[i][j - 1] + ile[j][i];
        }
    }
}

int ile_w[N][N];

void count_ile_w(int n){
    for(int i = 1; i <= n; i++){
        int akt = 0;
        for(int j = 1; j <= n; j++){
            ile_w[i][j] = akt;
            akt += (p[j] > i);
        }
    }
}

int s[N][N];

void count_s(int n){
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= n; j++){
            s[i][j] = s[i][j - 1] + ile_w[i][poz[j]];
        }
    }
}
int v[N][N];

void count_v(int n){
    count_ile(n);
    count_ile_w(n);
    count_s(n);
    count_inw(n);
    for(int i = 1; i <= n; i++){
        for(int j = i; j <= n; j++){
            v[i][j] = inw[i][j] + s[j][j] - s[j][i - 1];
        }
    }
}

int dp[N][N];

void count_dp(int n){
    count_v(n);
    for(int i = 1; i <= n; i++){
        int x = INF;
        for(int j = i - 1; j > 0; j--) x = min(x, dp[j][i - j]);
        if(x == INF) x = 0;
        for(int j = 1; j <= (n - i + 1); j++){
            dp[i][j] = v[i][i + j - 1] + x;
        }
    }
}
signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(NULL); cout.tie(NULL);
    // random_device rd;
    // mt19937_64 gen(rd());
    int n;
    cin >> n;
    for(int i = 1; i <= n; i++){
        cin >> p[i];
        poz[p[i]] = i;
    }
    count_dp(n);
    int ans = INF;
    for(int i = 1; i <= n; i++) ans = min(ans, dp[i][n - i + 1]);
    cout << ans << "\n";
    return 0;
}

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