Submission #674758

#	Time	Username	Problem	Language	Result	Execution time	Memory
674758		QwertyPi	Feast (NOI19_feast)	C++14	0 / 100	829 ms	23720 KiB

feast

#include <bits/stdc++.h>
#define int long long
using namespace std;

const int MAXN = 3e5 + 11;
long double a[MAXN], dp[MAXN], dp2[MAXN], c[MAXN], c2[MAXN];

int32_t main(){
	int n, k; cin >> n >> k;
	for(int i = 0; i < n; i++){
		cin >> a[i];
	}
	
	auto test = [&n](long double C) {
		fill(dp, dp + MAXN, -(1LL << 60));
		fill(dp2, dp2 + MAXN, -(1LL << 60));
		fill(c, c + MAXN, 0);
		fill(c2, c2 + MAXN, 0);
		dp[0] = -(1LL << 60), dp2[0] = 0;
		for(int j = 0; j < n; j++){
			if(dp2[j - 1] + a[j] - C >= dp[j] + a[j]){
				dp[j + 1] = dp2[j - 1] + a[j] - C;
				c[j + 1] = c2[j - 1] + 1;
			}else{
				dp[j + 1] = dp[j] + a[j]; 
				c[j + 1] = c[j];
			}
			if(dp2[j] >= dp[j + 1]){
				dp2[j + 1] = dp2[j];
				c2[j + 1] = c2[j];
			}else{
				dp2[j + 1] = dp[j + 1];
				c2[j + 1] = c[j + 1];
			}
		}
	};
	
	long double l = 0, r = 1 << 30;
	for(int tr = 0; tr < 60; tr++){
		int mid = (l + r) / 2;
		test(mid);
		if(c2[n] > k){
			l = mid;
		}else{
			r = mid;
		}
	}
	test(l); long double v1 = dp2[n] + l * c2[n], k1 = c2[n];
	test(r); long double v2 = dp2[n] + r * c2[n], k2 = c2[n];
	if(k1 == k2) cout << v1 << endl;
	else cout << v1 + (v2 - v1) / (k2 - k1) * (k - k1) << endl;
}

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