Submission #866153

#	Time	Username	Problem	Language	Result	Execution time	Memory
866153		green_gold_dog	Giraffes (JOI22_giraffes)	C++17	32 / 100	3 ms	860 KiB

giraffes

//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx,avx2,sse,sse2,sse3,ssse3,sse4,abm,popcnt,mmx")
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef double db;
typedef long double ldb;
typedef complex<double> cd;

constexpr ll INF64 = 9'000'000'000'000'000'000, INF32 = 2'000'000'000, MOD = 1'000'000'007;
constexpr db PI = acos(-1);
constexpr bool IS_FILE = false, IS_TEST_CASES = false;

random_device rd;
mt19937 rnd32(rd());
mt19937_64 rnd64(rd());

template<typename T>
bool assign_max(T& a, T b) {
        if (b > a) {
                a = b;
                return true;
        }
        return false;
}

template<typename T>
bool assign_min(T& a, T b) {
        if (b < a) {
                a = b;
                return true;
        }
        return false;
}

template<typename T>
T square(T a) {
        return a * a;
}

template<>
struct std::hash<pair<ll, ll>> {
        ll operator() (pair<ll, ll> p) const {
                return ((__int128)p.first * MOD + p.second) % INF64;
        }
};

void solve() {
        ll n;
        cin >> n;
        vector<ll> arr(n);
        for (ll i = 0; i < n; i++) {
                cin >> arr[i];
                arr[i]--;
        }
        vector<vector<ll>> dp(n + 1, vector<ll>(n + 1, 0));
        for (ll i = 1; i <= n; i++) {
                vector<vector<ll>> ndp(n + 1, vector<ll>(n + 1, 0));
                for (ll j = 0; j < i; j++) {
                        for (ll k = 0; k < i; k++) {
                                assign_max(ndp[j][k], dp[j][k]);
                                assign_max(ndp[j + 1][k], dp[j][k]);
                                assign_max(ndp[j][k + 1], dp[j][k]);
                                assign_max(ndp[j + 1][k + 1], dp[j][k]);
                                if (arr[j] == k) {
                                        assign_max(ndp[j + 1][k + 1], dp[j][k] + 1);
                                }
                                if (arr[j] == n - (i - k)) {
                                        assign_max(ndp[j + 1][k], dp[j][k] + 1);
                                }
                                if (arr[n - (i - j)] == k) {
                                        assign_max(ndp[j][k + 1], dp[j][k] + 1);
                                }
                                if (arr[n - (i - j)] == n - (i - k)) {
                                        assign_max(ndp[j][k], dp[j][k] + 1);
                                }
                        }
                }
                dp = ndp;
        }
        ll ans = 0;
        for (auto i : dp) {
                for (auto j : i) {
                        assign_max(ans, j);
                }
        }
        assert(ans <= 20);
        cout << n - ans << '\n';
}

int main() {
        if (IS_FILE) {
                freopen("", "r", stdin);
                freopen("", "w", stdout);
        }
        ios_base::sync_with_stdio(false);
        cin.tie(0);
        cout.tie(0);
        ll t = 1;
        if (IS_TEST_CASES) {
                cin >> t;
        }
        for (ll i = 0; i < t; i++) {
                solve();
        }
}

Compilation message (stderr)

giraffes.cpp: In function 'int main()':
giraffes.cpp:95:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   95 |                 freopen("", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~
giraffes.cpp:96:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   96 |                 freopen("", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~

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