Submission #942274

#	Time	Username	Problem	Language	Result	Execution time	Memory
942274		Litusiano	Feast (NOI19_feast)	C++17	51 / 100	32 ms	1024 KiB

feast

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int inf = 1e18;
vector<vector<int>> table;

int query(int l, int r){
	if (l > r) return inf;
    int len = r-l+1;
    int k = 63- __builtin_clzll(len);
    return min(table[l][k], table[r-(1<<k)+1][k]);
}


signed main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n,k;
	cin>>n>>k;
	if(k == 1){
		int bst = 0;
		int cur = 0;
		for(int i = 0; i<n; i++){
			int a; cin>>a;
			cur = max(0ll, cur+a);
			bst = max(bst,cur);
		}
		cout<<bst<<endl;
		return 0;
	}
	if(n > 300){
		int s = 0;
		for(int i = 0; i<n; i++){
			int a; cin>>a;
			s+= max(0ll,a);
		}
		cout<<s<<endl;
		return 0;
	}
	vector<int> v(n); for(int& i : v) cin>>i;
	vector<int> pre(n+1); for(int i =0 ; i<n; i++) pre[i+1] = pre[i] + v[i];
	table.resize(n+1, vector<int>(25,inf));
	for(int i = 0; i<=n; i++) table[i][0] = pre[i];
	for(int k = 1; k<25; k++){
		for(int i = 0; i<n; i++){
			int covers = i + (1<<k) -1;
			if(covers >= n) break;
			int nxt = i + (1<<(k-1));
			table[i][k] = min(table[i][k-1], table[nxt][k-1]);
		}
	}

	vector<vector<int>> dp(n+1, vector<int>(k+1,0)); // using i with i first, and k customers 
	for(int i = 0; i<=n; i++) dp[i][0] = 0;
	for(int j = 1; j<=k; j++){
		for(int i = 1; i<=n; i++){
			int idx = i-1;
			for(int z = 0; z<i; z++){
				dp[i][j] = max(dp[i][j], dp[z][j] + pre[i] - pre[z]);
				dp[i][j] = max(dp[i][j], dp[z][j-1] + pre[i] - query(z, i-1));
			}
		}
	}

	int ans = -inf;
	for(int i = 0; i<=n; i++) ans = max(ans, dp[i][k]);
	cout<<ans<<endl;

}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:57:8: warning: unused variable 'idx' [-Wunused-variable]
   57 |    int idx = i-1;
      |        ^~~

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