Submission #1291794

#	Time	Username	Problem	Language	Result	Execution time	Memory
1291794		tunademayo	Group Photo (JOI21_ho_t3)	C++20	0 / 100	0 ms	332 KiB

Main

#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define FOR(i, a, b) for(int i = a ; i <= b ; i++)
#define FORD(i, a, b) for(int i = a ; i >= b ; i--)
#define REP(i, a, b) for(int i = a ; i < b ; i++)

const bool Multitest = 0, Local = 0;

const int N = 5005;

int n, a[N], pos[N];

namespace sub1
{
    vector<int> v; int b[N];

    int check()
    {
        int cnt = 0;
        REP(i, 0, v.size())
        {
            if(i + 1 < v.size() && v[i] >= v[i + 1] + 2)
            {
                return 1e9;
            }
        }

        REP(i, 0, v.size()) cout << v[i] << ' '; cout << '\n';

        REP(i, 0, v.size())
        {
            b[i] = pos[v[i]];
        }


        REP(i, 0, v.size())
        {
            REP(j, i + 1, v.size())
            {
                if(b[i] > b[j]) cnt++;
            }
        }

        return cnt;
    }

    void solve()
    {
        for(int i = 0 ; i < n ; i++) v.push_back(i + 1);

        int ans = 1e9;

        do
        {
            ans = min(ans, check());
        } while(next_permutation(v.begin(), v.end()));

        cout << ans;
    }
}

namespace sub234
{
    const int Sub = 805;

    int dp[Sub], cost[Sub][Sub], val[Sub][Sub], b[Sub];

    int get(int p1, int p2)
    {
        int cnt = 0;

        FOR(i, 1, p1)
        {
            if(b[i] > b[p2]) cnt++;
        }

        return cnt;
    }

    void solve()
    {
        for(int i = 1 ; i <= n ; i++) b[i] = pos[i];

        for(int j = 1 ; j <= n ; j++)
        {
            for(int i = j ; i >= 1 ; i--)
            {
                val[i][j] = val[i + 1][j] + (b[i] < b[j]);
            }
        }

        for(int i = 1 ; i <= n ; i++)
        {
            for(int j = i ; j <= n ; j++)
            {
                cost[i][j] = cost[i][j - 1] + get(i - 1, j) + val[i][j];
            }
        }

//        cerr << val[1][2] << '\n';

        for(int i = 1 ; i <= n ; i++)
        {
            dp[i] = 1e9;
            for(int j = 1 ; j <= i ; j++)
            {
                dp[i] = min(dp[i], dp[j - 1] + cost[j][i]);
            }
        }
        cout << dp[n];
    }
}

void work()
{
    cin >> n;

    FOR(i, 1, n)    cin >> a[i], pos[a[i]] = i;

    if(n <= 9) sub1::solve();
    else if(n <= 800) sub234::solve();
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

    int q = 1;

    if(Local && fopen("code.inp", "r"))
    {
        freopen("code.inp", "r", stdin);
        freopen("code.ans", "w", stdout);
    }

    if(Multitest)   cin >> q;

    while(q--) work();
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:135:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  135 |         freopen("code.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:136:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  136 |         freopen("code.ans", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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