Submission #829369

#	Time	Username	Problem	Language	Result	Execution time	Memory
829369		QwertyPi	Uplifting Excursion (BOI22_vault)	C++14	80 / 100	5087 ms	456076 KiB

vault

#include <bits/stdc++.h>
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("Ofast")
#define int long long

using namespace std;

const int M = 300 + 11;
const int X = M * M * 2;
const int INF = 1LL << 60;
int a[M * 2];
int s[M * 2];

int norm(int x, int m){
	if(x >= 0) return x;
	return (x % m + m) % m;
}

int dp_p[M][X], dp_n[M][X];
void solve(int m, int L, vector<int> a, int dp[M][X]){
	for(int i = 0; i <= m; i++){
		fill(dp[i], dp[i] + X, -INF);
	}
	for(int i = 1; i <= m; i++) s[i] = min(L, s[i - 1] + i * a[i]);

	dp[0][0] = 0;
	for(int i = 1; i <= m; i++){
		for(int j = 0; j <= m * m + m * (i - 1); j++){
			int left = norm(s[i] - s[i - 1] + j - a[i] * i, i);
			int right = min(s[i] + j - s[i - 1], m * m + m * i);
			int inc = i;
			int delta = ((s[i] - left) - (s[i - 1] - j)) / i;
			for(int k = left; k <= right; k += inc){
				dp[i][k] = max(dp[i][k], dp[i - 1][j] + delta);
				delta--;
			}
		}
	}
}

int32_t main(){
	int m, L; cin >> m >> L;
	for(int i = 0; i <= m * 2; i++) cin >> a[i];
	
	if(L < 0){
		reverse(a, a + m * 2 + 1); L = -L;
	}

	int sum_p = 0, sum_n = 0;
	for(int i = m + 1; i <= m * 2; i++) {
		sum_p += (i - m) * a[i];
	}
	for(int i = m - 1; i >= 0; i--) {
		sum_n += (m - i) * a[i];
	}

	if(sum_p < L){
		cout << "impossible" << endl;
		return 0;
	}

	int lim = min(sum_n, sum_p - L);

	// positive
	vector<int> b_pos {0}, b_neg {0};
	for(int i = 1; i <= m; i++){
		b_pos.push_back(a[m + i]);
		b_neg.push_back(a[m - i]);
	}

	solve(m, lim + L, b_pos, dp_p);
	solve(m, lim, b_neg, dp_n);

	int ans = -INF;
	for(int i = 0; i <= m * m * 2; i++){
		ans = max(ans, dp_p[m][i] + dp_n[m][i]);
	}
	if(L < 0){
		cout << "impossible" << endl;
		return 0;
	}

	if(ans <= -INF / 2){
		cout << "impossible" << endl;
	}else{
		cout << a[m] + ans << endl;
	}
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3-1: 10 / 10
• Subtask 3-2: 10 / 10
• Subtask 4-1: 10 / 10
• Subtask 4-2: 10 / 10
• Subtask 5-1: 10 / 10
• Subtask 5-2: 10 / 10
• Subtask 6-1: 0 / 10
• Subtask 6-2: 0 / 10