Submission #1291544

#	Time	Username	Problem	Language	Result	Execution time	Memory
1291544		MrDogMeat	Giraffes (JOI22_giraffes)	C++20	32 / 100	194 ms	580 KiB

giraffes

#include<bits/stdc++.h>

using namespace std;

const int MAXN = 8e3;
const int INF32 = 1e9;

///vector
#define SZ(x) (int)x.size()

///input
int N;
int P[MAXN+5];

namespace sub1 {
    int Ans = INF32;

    bool check(const vector<int>& P) {
        for(int l = 0; l < N; l++)
        {
            for(int r = 0; r < N; r++)
            {
                bool cond1 = false, cond2 = false;
                for(int i = l; i <= r; i++)
                {
                    if(P[i] > P[l] && P[i] > P[r]) cond1 = true;
                    if(P[i] < P[l] && P[i] < P[r]) cond2 = true;
                }
                if(cond1 && cond2) return false;
            }
        }
        return true;
    }

    void solution() {
        vector<int> perm(N);
        for(int i = 0; i < N; i++) {
            perm[i] = i + 1;
        }
        do {
            if(check(perm)) {
                int cnt = 0;
                for(int i = 1; i <= N; i++) {
                    if(P[i] != perm[i - 1]) cnt++;
                }
                Ans = min(Ans, cnt);
            }
        } while(next_permutation(perm.begin(), perm.end()));
        cout << Ans;
    }

    bool check() {
        return (N <= 7);
    }
}

namespace sub2 {
    int Ans = INF32;
    int tmp[4];

    void brute_force(int l, int r, int Min, int Max, int cnt) {
        if(l > r) {
            Ans = min(Ans, cnt);
            return;
        }

        tmp[0] = cnt;
        if(P[l] != Min) tmp[0]++;
        brute_force(l + 1, r, Min + 1, Max, tmp[0]);
        tmp[1] = cnt;
        if(P[l] != Max) tmp[1]++;
        brute_force(l + 1, r, Min, Max - 1, tmp[1]);
        tmp[2] = cnt;
        if(P[r] != Min) tmp[2]++;
        brute_force(l, r - 1, Min + 1, Max, tmp[2]);
        tmp[3] = cnt;
        if(P[r] != Max) tmp[3]++;
        brute_force(l, r - 1, Min, Max - 1, tmp[3]);
    }

    void solution() {
        brute_force(1, N, 1, N, 0);
        cout << Ans;
    }

    bool check() {
        return (N <= 13);
    }
}

void solution() {
    cin >> N;
    for(int i = 1; i <= N; i++) {
        cin >> P[i];
    }

    if(sub1::check()) return sub1::solution();
    if(sub2::check()) return sub2::solution();
}

#define FILE "task"
main() {
    if(fopen(FILE".in","r")) {
        freopen(FILE".in","r",stdin);
        freopen(FILE".ans","w",stdout);
    }
    cin.tie(nullptr)->ios_base::sync_with_stdio(false);

    solution();

    cerr << "\n" << clock() << " ms";
    return 0;
}

Compilation message (stderr)

giraffes.cpp:102:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  102 | main() {
      | ^~~~
giraffes.cpp: In function 'int main()':
giraffes.cpp:104:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  104 |         freopen(FILE".in","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
giraffes.cpp:105:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  105 |         freopen(FILE".ans","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 22 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 41