Submission #668882

#	Time	Username	Problem	Language	Result	Execution time	Memory
668882		mychecksedad	The short shank; Redemption (BOI21_prison)	C++17	10 / 100	60 ms	12316 KiB

prison

/* Author : Mychecksdead */
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
#define pb push_back
#define all(x) x.begin(), x.end()
const int N = 2e6+10, M = 5e3 + 10, MOD = 1e9+7;


int n, d, a[N], T, dp[M][M][2], pref[N][2], suf[N], ans, pre[M][M];

void solve(){
	cin >> n >> d >> T;

	for(int i = 1; i <= n; ++i) cin >> a[i];
	
	pref[0][0] = 0, pref[0][1] = MOD, suf[n + 1] = 0;
	int cur = MOD;
	
	for(int i = 1; i <= n; ++i){
		pref[i][0] = pref[i - 1][0];
		if(min(a[i], cur) <= T) pref[i][0]++;
		cur = min(a[i] + 1, cur + 1);
		pref[i][1] = cur - 1;
	}
	
	ans = n;

	if(n > 5000){
		deque<pair<int, int>> q;
		
		for(int i = n; i >= 1; --i){
			suf[i] = suf[i + 1];
			q.push_front({a[i], i});
			while(!q.empty()){
				if(min(q.front().first, a[i] + q.front().second - i) <= T){
					suf[i]++;
					q.pop_front();
				}else{
					break;
				}
			}
		}
		
		for(int i = 0; i <= n; ++i){
			ans = min(ans, pref[i][0] + suf[i + 1]);
		}
	}else{
		for(int i = 0; i <= n; ++i) for(int j = 0; j <= n; ++j) pre[i][j] = 0;
		for(int i = 1; i <= n; ++i){
			pre[i][i] = a[i] <= T;
			int cur = a[i] + 1;
			for(int j = i + 1; j <= n; ++j){
				pre[i][j] = pre[i][j - 1];
				if(min(a[j], cur) <= T) pre[i][j]++;
				cur = min(a[j] + 1, cur + 1);
			}
		}


		for(int i = 0; i <= n; ++i) for(int j = 0; j <= n; ++j) dp[i][j][0] = (j == 0 ? pref[i][0] : n), dp[i][j][1] = pref[i][1];

		dp[0][0][0] = 0;
		dp[0][0][1] = MOD;
		for(int i = 1; i <= n; ++i){
			bool is = a[i] <= T;
			for(int j = 1; j <= d; ++j){
				bool added = min(a[i], dp[i - 1][j][1] + 1) <= T;
				if(dp[i - 1][j - 1][0] + is > dp[i - 1][j][0] + added){
					dp[i][j][0] = dp[i - 1][j][0] + added;
					dp[i][j][1] = min(a[i], dp[i - 1][j][1] + 1);
				}else{
					dp[i][j][0] = dp[i - 1][j - 1][0] + is;
					dp[i][j][1] = a[i];
				}
			}
		}
		ans = dp[n][d][0];
	}
	
	cout << ans;
}




int main(){
    cin.tie(0); ios::sync_with_stdio(0);
    solve();
    return 0;
 
}

• Subtask 1: 0 / 15
• Subtask 2: 10 / 10
• Subtask 3: 0 / 20
• Subtask 4: 0 / 10
• Subtask 5: 0 / 25
• Subtask 6: 0 / 20