Submission #1303125

#	Time	Username	Problem	Language	Result	Execution time	Memory
1303125		aaaaaaaa	Building Bridges (CEOI17_building)	C++20	100 / 100	63 ms	11992 KiB

building

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int inf = -(1LL << 62);
struct line {
  int m, b;
  mutable function<const line*() > succ;
  bool operator < (const line& rhs) const {
    if (rhs.b != inf) return m < rhs.m;
    const line* s = succ();
    if (!s) return 0;
    int x = rhs.m;
    return b - s->b < (s->m - m) * x;
  }
};
struct CHT : public multiset<line> {
  bool bad(iterator y) {
    auto z = next(y);
    if (y == begin()) {
      if (z == end()) return 0;
      return y -> m == z -> m && y -> b <= z -> b;
    }
    auto x = prev(y);
    if (z == end()) return y -> m == x -> m && y -> b <= x -> b;
    return 1.0 * (x -> b - y -> b) * (z -> m - y -> m) >= 1.0 * (y -> b - z -> b) * (y -> m - x -> m);
  }
  void add(int m, int b) {
    auto y = insert({ m, b });
    y->succ = [=, this] { return next(y) == end() ? 0 : &*next(y); };
    if (bad(y)) {
      erase(y);
      return;
    }
    while (next(y) != end() && bad(next(y))) erase(next(y));
    while (y != begin() && bad(prev(y))) erase(prev(y));
  }
  int query(int x) {
    assert(!empty());
    auto l = *lower_bound((line) {
      x, inf
    });
    return l.m * x + l.b;
  }
};
CHT* cht;
signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr); cout.tie(nullptr);
    int n;
    cin >> n;
    vector<int> h(n + 1, 0), w(n + 1, 0);
    for(int i = 1; i <= n; ++i){
        cin >> h[i];
    }
    for(int i = 1; i <= n; ++i){
        cin >> w[i];
        w[i] += w[i - 1];
    }
    vector<int> dp(n + 5, 0);
    cht = new CHT();
    cht -> add (2 * h[1], -(h[1] * h[1] - w[1]));
    for(int i = 2; i <= n; ++i){
        dp[i] = -cht -> query(h[i]) + h[i] * h[i] + w[i - 1];
        cht -> add(2 * h[i], -(dp[i] + h[i] * h[i] - w[i]));
    }
    cout << dp[n] << "\n";
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40