Submission #731006

#TimeUsernameProblemLanguageResultExecution timeMemory
731006rembocoderAliens (IOI16_aliens)C++17
60 / 100
2072 ms12788 KiB
#include "aliens.h" #include <bits/stdc++.h> using namespace std; bool cmp(const pair<int, int>& a, const pair<int, int>& b) { if (a.first != b.first) { return a.first < b.first; } return a.second > b.second; } long long divide_up(long long a, long long b) { if (b < 0) { a = -a; b = -b; } if (a < 0) { return a / b; } else { return (a + b - 1) / b; } } long long take_photos(int n, int m, int k, vector<int> points_x, vector<int> points_y) { vector<pair<int, int>> points(n); for (int i = 0; i < n; i++) { if (points_x[i] > points_y[i]) { swap(points_x[i], points_y[i]); } points[i] = {points_x[i], points_y[i] + 1}; } sort(points.begin(), points.end(), cmp); vector<pair<int, int>> points_fin; points_fin.push_back({-1, -1}); int max_y = -1; for (int i = 0; i < n; i++) { if (max_y < points[i].second) { max_y = points[i].second; points_fin.push_back(points[i]); } } points = points_fin; points_fin.clear(); n = points.size(); vector<long long> l(n), r(n); for (int i = 0; i < n; i++) { l[i] = points[i].first; r[i] = points[i].second; } vector<long long> b(n); for (int i = 0; i < n - 1; i++) { b[i] = 2 * l[i + 1]; } k = min(k, n - 1); vector<long long> dp(n, 2e12); dp[0] = 0; for (int p = 0; p < k; p++) { vector<long long> a(n); for (int i = 0; i < n - 1; i++) { a[i] = dp[i] + l[i + 1] * l[i + 1] - max(0ll, r[i] - l[i + 1]) * max(0ll, r[i] - l[i + 1]); } vector<pair<long long, int>> ch; // {x, ind} – начиная с такого r[i] лучше всего переходить из ind ch.push_back({-1, p}); int cur = 0; vector<long long> new_dp(n, 2e12); for (int i = p + 1; i < n; i++) { while (cur + 1 < ch.size() && ch[cur + 1].first <= r[i]) { cur++; } int j = ch[cur].second; new_dp[i] = r[i] * r[i] + a[j] - b[j] * r[i]; if (i == n - 1) { continue; } while (ch.size()) { long long x = ch.back().first; int j = ch.back().second; if (a[j] - b[j] * x < a[i] - b[i] * x) { break; } ch.pop_back(); } if (ch.empty()) { ch.push_back({-1, i}); } else { int j = ch.back().second; ch.push_back({max(divide_up(a[i] - a[j], b[i] - b[j]), -1ll), i}); } cur = min(cur, int(ch.size()) - 1); } dp = new_dp; } return dp.back(); } // dp[p][i] = min_j( dp[p - 1][j] + (r[i] - l[j + 1])^2 - max(0, r[j] - l[j + 1])^2 ) // dp[p][i] = r[i]^2 + min_j( dp[p - 1][j] + l[j + 1]^2 - max(0, r[j] - l[j + 1])^2 - 2 l[j + 1] r[i] )

Compilation message (stderr)

aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:69:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   69 |             while (cur + 1 < ch.size() && ch[cur + 1].first <= r[i]) {
      |                    ~~~~~~~~^~~~~~~~~~~
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