Submission #976681

#	Time	Username	Problem	Language	Result	Execution time	Memory
976681		vjudge1	Watching (JOI13_watching)	C++17	100 / 100	619 ms	31940 KiB

watching

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define lld double
#define int ll
#define usaco(fname) freopen(#fname ".in","r",stdin);freopen(#fname ".out","w",stdout);
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
// const ll INF = 1e18;
const int INF = 1e18;
const int mod = 1e9+7;
const lld PI = acos(-1.0);
int di[] = {1, -1, 0, 0, 1, 1, -1, -1};
int dj[] = {0, 0, 1, -1, 1, -1, 1, -1};
#define debug(x) cout << #x << ": " << x << endl;
#define add(a, b) a += b, a %= mod
#define mul(a, b) ((a % mod) * (b % mod)) % mod
#define all(x) x.begin(),x.end()

void solve() {
  int n,p,q;cin>>n>>p>>q;
  vector<int> a(n);
  for (int i =0 ; i < n; i++) cin >> a[i];
  sort(all(a));

  int Q = min(q, n);
  function<bool(int)> chk = [&](int k) {
    // dp[i][q]
    vector<vector<int>> dp(n, vector<int>(Q+1, INF));
    for (int i = 0; i < n; i++) {
      // we use K or 2*K here
      int j1 = lower_bound(all(a), a[i] + k) - a.begin();j1--;
      int j2 = lower_bound(all(a), a[i] + 2*k) - a.begin();j2--;

      for (int j = 0; j <= Q; j++) {
        int before = (i-1 >= 0 ? dp[i-1][j] : 0);
        // for addition of P
        dp[j1][j] = min(dp[j1][j], before + 1);

        if (j+1 <= Q) dp[j2][j+1] = min(dp[j2][j+1], before);
      }
    }

    for (int i = 0; i <= Q; i++) {
      if (dp[n-1][i] <= p) return true;
    }
    return false;
  };

  int ans = 1e9+69;
  int l = 1, r = 1e9+69;
  while (l <= r) {
    int mid = (l+r)>>1;

    if (chk(mid)) {
      r = mid-1;
      ans = mid;
    } else l = mid+1;
  }

  cout << ans << endl;
}

int32_t main() {
  ios_base::sync_with_stdio(0);cin.tie(0);
  int t=1;
  while(t--) solve();

  return 0;
}

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