Submission #1233327

#	Time	Username	Problem	Language	Result	Execution time	Memory
1233327		CrabCNH	Watching (JOI13_watching)	C++20	100 / 100	253 ms	15232 KiB

watching

#include <bits/stdc++.h>

#define task     "BriantheCrab"

#define pii    pair <int, int>
#define fi     first
#define se     second
#define szf    sizeof
#define sz(s)  (int)((s).size())
#define all(v) (v).begin(), (v).end()

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

using namespace std;

template <class T> void minimize (T &t, T f) {if (t > f) t = f;}
template <class T> void maximize (T &t, T f) {if (t < f) t = f;}

const int maxN = 2e3 + 5;
const int inf = 1e9 + 7;
const int mod = 1e2 + 7;

// khong tu code thi khong kha len duoc dau

int n, P, Q;
int a[maxN];

bool check (int w) {
    vector <vector <int>> dp (n + 2, vector <int> (P + 2, inf));
    for (int i = 0; i <= P; i ++) {
        dp[0][i] = 0;
    }
    int curP = 0, curQ = 0;
    for (int i = 1; i <= n; i ++) {
        while (a[i] - a[curP] + 1 > w && curP < i) {
            curP ++;
        }
        while (a[i] - a[curQ] + 1 > w * 2 && curQ < i) {
            //cout << "cc " << a[i] << ' ' << a[curQ] << '\n'; 
            curQ ++;
            //cout << a[i] - a[curQ] << ' ' << w * 2 << '\n';
        }
        curP -= ((a[i] - a[curP] + 1 <= w) && (curP >= 1));
        curQ -= ((a[i] - a[curQ] + 1 <= 2 * w) && (curQ >= 1));
        for (int j = 0; j <= P; j ++) {
           // cout << "trace " << i << ' ' << curP << ' ' << curQ << '\n';
            if (j >= 1) {
                minimize (dp[i][j], dp[curP][j - 1]);
            }
            minimize (dp[i][j], dp[curQ][j] + 1);
            //cout << i << ' ' << j << ' ' << dp[i][j] << '\n';
            //if (j >= 1) cout << "tr " << curP << ' ' << j - 1 << ' ' << dp[curP][j - 1] << '\n';
            //cout << "tr " << curQ << ' ' << j << ' ' << dp[curQ][j] + 1 << '\n';
        }
    }
    for (int i = 0; i <= P; i ++) {
        //cout << dp[n][i] << '\n';
        if (dp[n][i] <= Q) {
            return true;
        }
    }
    return false;
}

void solve () {
    cin >> n >> P >> Q;
    for (int i = 1; i <= n; i ++) {
        cin >> a[i];
    }
    if (P + Q >= n) {
        cout << 1;
        return;
    }
    sort (a + 1, a + n + 1);
    int l = 0, r = inf, res = -1;
    while (true) {
        if (l > r) {
            break;
        }
        int mid = (l + r) >> 1;
        if (check (mid)) {
            res = mid;
            r = mid - 1;
        }
        else {
            l = mid + 1;
        }
    }
    cout << res;
    return;
}

signed main () {
    cin.tie (nullptr) -> sync_with_stdio (false);
    if (fopen (task".inp", "r")) {
        freopen (task".inp", "r", stdin);
        freopen (task".out", "w", stdout);
    }
    int t = 1;
    //cin >> t;
    while (t --) {
        solve ();
    } 
    return 0;
}
// thfv

Compilation message (stderr)

watching.cpp: In function 'int main()':
watching.cpp:98:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   98 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
watching.cpp:99:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   99 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50