제출 #107211

#제출 시각아이디문제언어결과실행 시간메모리
107211tictaccatAliens (IOI16_aliens)C++14
60 / 100
2125 ms777048 KiB
#include "aliens.h" #include <bits/stdc++.h> using namespace std; typedef long long ll; const ll INF = (ll)1e18; ll ccw (pair<ll,ll> p1, pair<ll,ll> p2, pair<ll,ll> p3) { return (p2.first-p1.first)*(p3.second-p2.second) - (p2.second-p1.second)*(p3.first-p2.first); } struct Hull { vector<pair<ll,ll>> hull; ll p = 0; void insert(pair<ll,ll> p) { //points inserted with increasing x // if (hull.size()) assert(p.first >= hull.back().first); while (hull.size() >= 2 && ccw(hull[hull.size()-2],hull.back(),p) < 0) hull.pop_back(); hull.push_back(p); } ll query(ll k) { //minimise y-kx while (p < hull.size()-1 && -k*hull[p].first + hull[p].second > -k*hull[p+1].first + hull[p+1].second) p++; return -k*hull[p].first + hull[p].second; // ll low = INF; // for (auto p: hull) low = min(low,-k*p.first+p.second); // return low; } }; ll take_photos(int n, int m, int k, vector<int> ri, vector<int> ci) { vector<pair<ll,ll>> points; for (int i = 0; i < n; i++) points.push_back(make_pair(max(ci[i],ri[i]),min(ri[i],ci[i]))); sort(points.begin(),points.end()); vector<ll> r,c; //such that r_i < r_j, c_i < c_j for (int i = 0; i < n; i++) { while (r.size() > 0 && points[i].second <= r.back()) { r.pop_back(); c.pop_back(); } r.push_back(points[i].second); c.push_back(points[i].first); } n = r.size(); // for (int i = 0; i < n; i++) cout << r[i] << " " << c[i] << "\n"; vector<vector<ll>> dp(k+1, vector<ll> (n+1,INF)); //dp[k][i] = min squares covered over the first i points, using k segments vector<Hull> hulls(k+1); for (int u = 0; u <= k; u++) { dp[u][0] = 0; hulls[u].insert(make_pair(2*r[0],r[0]*r[0]-2*r[0])); } for (int i = 1; i <= n; i++) { for (int u = 1; u <= k; u++) { dp[u][i] = (c[i-1]+1)*(c[i-1]+1) + hulls[u-1].query(c[i-1]); ll overlap; if (c[i-1] < r[i]) overlap = 0LL; else overlap = (c[i-1]-r[i]+1)*(c[i-1]-r[i]+1); if (i < n) hulls[u].insert(make_pair(2*r[i],dp[u][i] + r[i]*r[i]-2*r[i]-overlap)); } } return dp[k][n]; } // int main() { // Hull test; // test.insert({3,4}); // test.insert({3,4}); // test.insert({5,1}); // cout << test.query(0) << "\n"; // }

컴파일 시 표준 에러 (stderr) 메시지

aliens.cpp: In member function 'll Hull::query(ll)':
aliens.cpp:21:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
        while (p < hull.size()-1 && -k*hull[p].first + hull[p].second > -k*hull[p+1].first + hull[p+1].second) p++;
               ~~^~~~~~~~~~~~~~~
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