Submission #543389

#	Time	Username	Problem	Language	Result	Execution time	Memory
543389		fcw	Feast (NOI19_feast)	C++17	40 / 100	315 ms	15064 KiB

feast

#include <bits/stdc++.h>
#define st first
#define nd second
using lint = int64_t;
constexpr int mod = int(1e9) + 7;
constexpr int inf = 0x3f3f3f3f;
constexpr int ninf = 0xcfcfcfcf;
constexpr lint linf = 0x3f3f3f3f3f3f3f3f;
const long double pi = acosl(-1.0);
// Returns -1 if a < b, 0 if a = b and 1 if a > b.
int cmp_double(double a, double b = 0, double eps = 1e-9) {
	return a + eps > b ? b + eps > a ? 0 : 1 : -1;
}
using namespace std;

const lint INF = 3e14 + 10;

int main() {
	cin.tie(nullptr)->sync_with_stdio(false);
	int n, k;
	cin>>n>>k;
	vector<lint>a(n);
	for(int i=0;i<n;i++) cin>>a[i];
	double lo = 0, hi = INF;
	for(int i=0;i<100;i++){
		double mid = (lo + hi) / 2;
		vector<array<pair<double, lint>, 2>>dp(n+1); 
		dp[0][0] = {0, 0}, dp[0][1] = {-INF, 0};
		for(int i=0;i<n;i++){
			dp[i+1][1] = max(make_pair(dp[i][1].st + a[i], dp[i][1].nd), 
					make_pair(dp[i][0].st + a[i] - mid, dp[i][0].nd + 1));
				
			dp[i+1][0] = max(dp[i][0], dp[i][1]);	
		}
		if(max(dp[n][0], dp[n][1]).nd >= k) lo = mid;
		else hi = mid; 
	}
	double mid = hi;
	vector<array<double, 2>>dp(n+1); 
	dp[0][0] = 0, dp[0][1] = -INF;
	for(int i=0;i<n;i++){
		dp[i+1][1] = max(dp[i][1] + a[i], dp[i][0] + a[i] - mid);
		dp[i+1][0] = max(dp[i][0], dp[i][1]);	
	}
	cout<< lint(max(dp[n][0], dp[n][1]) + mid * k + 1e-9)<<"\n";	
	
		
	
	

	return 0;
}
/*
[  ]Leu o problema certo???
[  ]Ver se precisa de long long
[  ]Viu o limite dos fors (é n? é m?)
[  ]Tamanho do vetor, será que é 2e5 em vez de 1e5??
[  ]Testar sample
[  ]Testar casos de  borda
[  ]1LL no 1LL << i
[  ]Testar mod (é 1e9+7, mesmo?, será que o mod não ficou negativo?)
*/

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 0 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29