Submission #555793

#	Time	Username	Problem	Language	Result	Execution time	Memory
555793		MilosMilutinovic	Aliens (IOI16_aliens)	C++14	0 / 100	1 ms	212 KiB

aliens

#include "aliens.h"
#include <bits/stdc++.h>

using namespace std;

const int MAX = 1000005;

struct Line {
  long long k, n;
  Line() {}
  Line(long long _k, long long _n) : k(_k), n(_n) {}
  long long get(long long x) {
    return k * x + n;
  }
};

int root, ls[4 * MAX], rs[4 * MAX], tsz;
Line st[4 * MAX];

void modify(int& node, int l, int r, Line k) {
  if (!node) {
    node = ++tsz;
    st[node] = k;
    return;
  }
  long long a = st[node].get(l);
  long long b = k.get(l);
  long long c = st[node].get(r);
  long long d = k.get(r);
  if (a >= b && c >= d) {
    return;
  }
  if (a <= b && c <= d) {
    st[node] = k;
    return;
  }
  int mid = l + r >> 1;
  if (a <= b) {
    swap(st[node], k);
  }
  if (st[node].get(mid) >= k.get(mid)) {
    modify(rs[node], mid + 1, r, k);
  } else {
    swap(st[node], k);
    modify(ls[node], mid, l, k);
  }
}

long long query(int node, int l, int r, int i) {
  if (!node) {
    return -1e18;
  }
  if (l == r) {
    return st[node].get(i);
  }
  long long val = st[node].get(i);
  int mid = l + r >> 1;
  if (i <= mid) {
    val = max(val, query(ls[node], l, mid, i));
  } else {
    val = max(val, query(rs[node], mid + 1, r, i));
  }
  return val;
}

void build() {
  for (int i = 1; i <= tsz; i++) {
    ls[i] = 0;
    rs[i] = 0;
  }
  root = 0;
  tsz = 0;
}

long long take_photos(int n, int m, int k, vector<int> r, vector<int> c) {
  for (int i = 0; i < n; i++) {
    if (r[i] > c[i]) {
      swap(r[i], c[i]);
    }
  }
  vector<int> order(n);
  iota(order.begin(), order.end(), 0);
  sort(order.begin(), order.end(), [&](int i, int j) {
    if (r[i] != r[j]) {
      return r[i] < r[j];
    } else {
      return c[i] > c[j];
    }
  });
  vector<pair<int, int>> pts;
  int mx = -1;
  for (int id = 0; id < n; id++) {
    int i = order[id];
    if (c[i] <= mx) {
      continue;
    } else {
      mx = max(mx, c[i]);
      pts.emplace_back(r[i], c[i]);
    }
  }
  n = (int) pts.size();
  for (int i = 0; i < n; i++) {
    r[i] = pts[i].first;
    c[i] = pts[i].second;
  }
  vector<long long> w(n);
  for (int i = 1; i < n; i++) {
    long long d = c[i - 1] - r[i] + 1;
    if (d < 0) {
      continue;
    }
    w[i - 1] = d * d;
  }
  const long long inf = (long long) 1e18;
  vector<long long> dp(n, inf);
  for (int t = 0; t < k; t++) {
    vector<long long> new_dp(n, inf);
    build();
    for (int i = 0; i < n; i++) {
      new_dp[i] = -query(1, 0, MAX, c[i] + 1) + (c[i] + 1) * 1LL * (c[i] + 1);
      long long ft = 0;
      if (i > 0) {
        ft = dp[i - 1];
      }
      new_dp[i] = min(new_dp[i], ft + (c[i] - r[i] + 1) * 1LL * (c[i] - r[i] + 1));
      modify(root, 0, MAX, Line(2 * r[i], -(r[i] * 1LL * r[i] + (i == 0 ? 0LL : ft - w[i]))));
      /*
      ft = (c[i] + 1 - r[j]) ^ 2 - w[j]
      ft = (c[i] + 1) ^ 2 - 2 * (c[i] + 1) * r[j] + r[j] ^ 2
      */
    }
    /* for (int i = 0; i < n; i++) {
      for (int j = 0; j <= i; j++) {
        long long d = c[i] - r[j] + 1;
        long long ft = d * d;
        if (j > 0) {
          ft += dp[j - 1] - w[j - 1];
        }
        new_dp[i] = min(new_dp[i], ft);
      }
    } */
    swap(dp, new_dp);
  }
  return dp[n - 1];
}
/*
5 7 2
0 3
4 4
4 6
4 5
4 6

*/

Compilation message (stderr)

aliens.cpp: In function 'void modify(int&, int, int, Line)':
aliens.cpp:37:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   37 |   int mid = l + r >> 1;
      |             ~~^~~
aliens.cpp: In function 'long long int query(int, int, int, int)':
aliens.cpp:57:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   57 |   int mid = l + r >> 1;
      |             ~~^~~

• Subtask 1: 0 / 4
• Subtask 2: 0 / 12
• Subtask 3: 0 / 9
• Subtask 4: 0 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 40