제출 #388087

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
388087		blue	Group Photo (JOI21_ho_t3)	C++17	100 / 100	399 ms	165320 KiB

Main

#include <iostream>
using namespace std;


int inv[5001][5001];

int main()
{
    int N;
    cin >> N;

    int H[N+1], pos[N+1];
    for(int i = 1; i <= N; i++) cin >> H[i];

    for(int i = 1; i <= N; i++) pos[ H[i] ] = i;

    int lowct[N+1][N+1]; //number of positions <= j with value greater than i
    for(int i = 1; i <= N; i++)
    {
        lowct[i][0] = 0;
        for(int j = 1; j <= N; j++)
        {
            lowct[i][j] = lowct[i][j-1] + (pos[j] > pos[i]);
        }
    }

    for(int i = 1; i <= N; i++)
    {
        inv[i][i] = 0;
        for(int j = i+1; j <= N; j++)
        {
            inv[i][j] = inv[i][j-1] + (lowct[j][j] - lowct[j][i-1]);
        }
    }
    for(int j = 0; j <= N; j++) inv[0][j] = inv[1][j];

    // for(int i = 1; i <= N; i++)
    // {
    //     cout << pos[i] << ' ';
    // }
    // cout << '\n';

    int dp[N+1];
    dp[0] = 0;
    for(int i = 1; i <= N; i++)
    {
        dp[i] = 1e9;
        for(int l = 1; l <= i; l++)
        {
            dp[i] = min(dp[i], dp[i-l] + l*(l-1)/2 - inv[i-l+1][i]  +  inv[1][i] - inv[1][i-l] - inv[i-l+1][i]);
            // cout << i-l+1 << ' ' << i << ' ' << l*(l-1)/2 - inv[i-l+1][i] << ' ' << inv[1][i] - inv[1][i-l] - inv[i-l+1][i] << ' ' << dp[i-l] << '\n';
        }
        // cout << dp[i] << ' ';
    }

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

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