Submission #577181

#	Time	Username	Problem	Language	Result	Execution time	Memory
577181		amunduzbaev	Tortoise (CEOI21_tortoise)	C++17	0 / 100	77 ms	196428 KiB

tortoise

#include "bits/stdc++.h"
using namespace std;
 
#define ar array
typedef int64_t ll;
//~ #define int int64_t

const int N = 5005;
const int inf = 1e9;
int dp[N][N], old[N][N], a[N];
int l[N], r[N], back[N][N];

signed main(){
	ios::sync_with_stdio(0); cin.tie(0);
	
	int n; cin>>n;
	for(int i=0;i<n;i++){
		l[i] = n;
		cin>>a[i];
		if(a[i] == -1) l[i] = 0;
		else if(i) l[i] = l[i-1] + 1;
	}
	for(int i=n-1;~i;i--){
		r[i] = n;
		if(a[i] == -1) r[i] = 0;
		else if(i + 1 < n) r[i] = r[i+1] + 1;
	}
	
	memset(dp, 63, sizeof dp);
	memset(back, 63, sizeof back);
	dp[0][0] = 0;
	int res = 0;
	for(int i=0;i<=n;i++){
		multiset<int> ss;
		for(int x=0;x<=n;x++){
			if(a[i] > 0){
				old[i][x] = dp[i][x] - x * 2 * min(l[i], r[i]);
				if(x){
					int tmp = inf;
					if(*ss.begin() + (x - 1) * 2 * min(l[i], r[i]) <= 2 * i){
						dp[i][x] = min(dp[i][x], *ss.begin() + x * 2 * min(l[i], r[i]));
						tmp = *ss.begin() + (x - 1) * 2 * min(l[i], r[i]);
					}
					
					if(i + r[i] < N){
						back[i + r[i]][x] = min(back[i + r[i]][x], tmp + r[i]);
					}
				}
				ss.insert(old[i][x]);
				if(x >= a[i]){
					ss.erase(ss.find(old[i][x - a[i]]));
				}
			}
			
			if(i + r[i] < N) dp[i][x] = min(dp[i][x], back[i + r[i]][x] + r[i]);
			dp[i+1][x] = min(dp[i+1][x], dp[i][x] + 1);
			if(dp[i][x] < inf){
				//~ cout<<i<<" "<<x<<" "<<dp[i][x]<<endl;;
				res = max(res, x);
				if(dp[i][x] < 2 * i) res = max(res, x + 1);
			}
		}
	}
	
	int tot = 0;
	for(int i=0;i<n;i++){
		if(~a[i]) tot += a[i];
	}
	
	cout<<tot - res<<"\n";
}

/*

7
4 2 0 2 5 2 -1 

*/

• Subtask 1: 0 / 8
• Subtask 2: 0 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 25
• Subtask 5: 0 / 27