Submission #554993

#	Time	Username	Problem	Language	Result	Execution time	Memory
554993		MilosMilutinovic	Building Bridges (CEOI17_building)	C++14	100 / 100	85 ms	66476 KiB

building

#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  vector<int> h(n);
  for (int i = 0; i < n; i++) {
    cin >> h[i];
  }
  vector<int> w(n);
  for (int i = 0; i < n; i++) {
    cin >> w[i];
  }
  vector<long long> pref(n);
  for (int i = 0; i < n; i++) {
    if (i > 0) {
      pref[i] = pref[i - 1];
    }
    pref[i] += w[i];
  }
  const int MAX = 1e6 + 5;
  vector<pair<long long, long long>> st(4 * MAX, {-1, -1});
  function<void(int, int, int, pair<long long, long long>)> modify = [&](int node, int l, int r, pair<long long, long long> line) {
    if (st[node].first == -1) {
      st[node] = line;
      return;
    }
    long long a = st[node].first * l + st[node].second;
    long long b = line.first * l + line.second;
    long long c = st[node].first * r + st[node].second;
    long long d = line.first * r + line.second;
    if (a >= b && c >= d) return;
    if (a <= b && c <= d) {
      st[node] = line;
      return;
    }
    int mid = l + r >> 1;
    if (a < b) {
      swap(st[node], line);
    }
    if (st[node].first * mid + st[node].second >= line.first * mid + line.second) {
      modify(node + node + 1, mid + 1, r, line);
    } else {
      swap(st[node], line);
      modify(node + node, l, mid, line);
    }
  };
  function<long long(int, int, int, int)> query = [&](int node, int l, int r, int i) {
    if (st[node].second == -1) {
      return (long long) -1e18;
    }
    if (l == r) {
      return st[node].first * i + st[node].second;
    }
    int mid = l + r >> 1;
    long long val = st[node].first * i + st[node].second;
    if (i <= mid) {
      val = max(val, query(node + node, l, mid, i));
    } else {
      val = max(val, query(node + node + 1, mid + 1, r, i));
    }
    return val;
  };
  modify(1, 0, MAX, {2 * h[0], -h[0] * 1LL * h[0] + w[0]});
  vector<long long> dp(n);
  for (int i = 1; i < n; i++) {
    dp[i] = query(1, 0, MAX, h[i]) - h[i] * 1LL * h[i] - pref[i - 1];
    modify(1, 0, MAX, {2 * h[i], -h[i] * 1LL * h[i] + pref[i] + dp[i]});
  }
  cout << -dp[n - 1] << '\n';
  return 0;
}

Compilation message (stderr)

building.cpp: In lambda function:
building.cpp:41:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   41 |     int mid = l + r >> 1;
      |               ~~^~~
building.cpp: In lambda function:
building.cpp:59:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   59 |     int mid = l + r >> 1;
      |               ~~^~~

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