Submission #530292

#	Time	Username	Problem	Language	Result	Execution time	Memory
530292		fhvirus	Cake 3 (JOI19_cake3)	C++17	24 / 100	4067 ms	5848 KiB

cake3

// Knapsack DP is harder than FFT.
#include<bits/stdc++.h>
using namespace std;
typedef long long ll; typedef pair<int,int> pii;
#define ff first
#define ss second
#define pb emplace_back
#define AI(x) begin(x),end(x)
#ifdef OWO
#define debug(args...) SDF(#args, args)
#define OIU(args...) ostream& operator<<(ostream&O,args)
#define LKJ(S,B,E,F) template<class...T>OIU(S<T...>s){O<<B;int c=0;for(auto i:s)O<<(c++?", ":"")<<F;return O<<E;}
LKJ(vector,'[',']',i)LKJ(deque,'[',']',i)LKJ(set,'{','}',i)LKJ(multiset,'{','}',i)LKJ(unordered_set,'{','}',i)LKJ(map,'{','}',i.ff<<':'<<i.ss)LKJ(unordered_map,'{','}',i.ff<<':'<<i.ss)
template<class...T>void SDF(const char* s,T...a){int c=sizeof...(T);if(!c){cerr<<"\033[1;32mvoid\033[0m\n";return;}(cerr<<"\033[1;32m("<<s<<") = (",...,(cerr<<a<<(--c?", ":")\033[0m\n")));}
template<class T,size_t N>OIU(array<T,N>a){return O<<vector<T>(AI(a));}template<class...T>OIU(pair<T...>p){return O<<'('<<p.ff<<','<<p.ss<<')';}template<class...T>OIU(tuple<T...>t){return O<<'(',apply([&O](T...s){int c=0;(...,(O<<(c++?", ":"")<<s));},t),O<<')';}
#else
#define debug(...) ((void)0)
#endif

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

	int N, M; cin >> N >> M;
	vector<pair<int, int>> cakes(N + 1);
	for (int i = 1; i <= N; ++i)
		cin >> cakes[i].second >> cakes[i].first;

	sort(begin(cakes) + 1, end(cakes));

	int64_t ans = LLONG_MIN;

	int64_t sum = 0;
	priority_queue<int, vector<int>, greater<int>> pq;
	auto add = [&](const int& v) -> void {
		pq.emplace(v);
		sum += v;
		if (pq.size() > M) {
			sum -= pq.top();
			pq.pop();
		}
	};

	auto solve = [&](const auto& solve, int l, int r, int sl, int sr) -> void {
		r = min(r, sr - M + 1);
		if (l > r) return;
		int m = (l + r) / 2;
		int bests = -1;
		int64_t bestv = LLONG_MIN;
		for (int i = m; i <= sr; ++i) {
			add(cakes[i].second);
			int64_t val = sum - 2ll * (cakes[i].first - cakes[m].first);
			if (pq.size() == M and bestv < val) {
				bests = i;
				bestv = val;
			}
		}
		assert(bests != -1);
		ans = max(ans, bestv);
		while (!pq.empty()) { sum -= pq.top(); pq.pop(); }
		if (l <= m - 1) solve(solve, l, m - 1, sl, bests);
		if (m + 1 <= r) solve(solve, m + 1, r, bests, sr);
	};

	solve(solve, 1, N - M + 1, M, N);

	cout << ans << '\n';

	return 0;
}

Compilation message (stderr)

cake3.cpp: In lambda function:
cake3.cpp:37:17: warning: comparison of integer expressions of different signedness: 'std::priority_queue<int, std::vector<int>, std::greater<int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   37 |   if (pq.size() > M) {
      |       ~~~~~~~~~~^~~
cake3.cpp: In instantiation of 'main()::<lambda(const auto:23&, int, int, int, int)> [with auto:23 = main()::<lambda(const auto:23&, int, int, int, int)>]':
cake3.cpp:64:33:   required from here
cake3.cpp:52:18: warning: comparison of integer expressions of different signedness: 'std::priority_queue<int, std::vector<int>, std::greater<int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   52 |    if (pq.size() == M and bestv < val) {
      |        ~~~~~~~~~~^~~~

• Subtask 1: 5 / 5
• Subtask 2: 19 / 19
• Subtask 3: 0 / 76