Submission #409148

#	Time	Username	Problem	Language	Result	Execution time	Memory
409148		8e7	Bigger segments (IZhO19_segments)	C++14	13 / 100	2 ms	2380 KiB

segments

//Challenge: Accepted
#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>
#include <stack>
#include <set>
#define ll long long
#define maxn 3005
#define mod 1000000007
#define pii pair<int, int>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
ll a[maxn], pref[maxn];
ll dp[maxn][maxn];
/*
int solve(int n) {
	for (int i = 0;i < n;i++) {
		for (int j = 0;j < n;j++) dp[i][j] = 0;
	}
	for (int i = 0;i < n;i++) {
		for (int j = 0;j <= i;j++) {
			dp[i][j] = -(1<<30);
			if (j == 0) {
				dp[i][j] = 1;
			} else {
				for (int k = j - 1;k >= 0;k--) {
					if (pref[i] - pref[j - 1] >= pref[j - 1] - (k ? pref[k - 1] :0)) {
						dp[i][j] = max(dp[i][j], dp[j - 1][k] + 1);
					}
				}
			}
		}
	}
	int ret = 0;
	for (int i = 0;i < n;i++) ret = max(ret, dp[n - 1][i]);
	return ret;
}
*/
int solve2(int n) {
	for (int i = 0;i < n;i++) dp[i][0] = pref[i];
	int ret = 1;
	int st = 0;
	for (int j = 1;j < n;j++) {
		int k = st;
		for (int i = st;i < n;i++) {
			dp[i][j] = 1LL<<60;
			int f = 0;
			while (k < n && pref[i] >= pref[k] + dp[k][j - 1]) f = 1, k++;
			if (f) k--;
			if (pref[i] >= pref[k] + dp[k][j - 1]){
				dp[i][j] = pref[i] - pref[k];
			} else {
				st++;
			}	
		}	
		if (st < n) {
			ret++;
		} else {
			break;
		}
	}
	return ret;
}
signed main() {
	io
	int n;
	cin >> n;
	for (int i = 0;i < n;i++)  {
		cin >> a[i];
		pref[i] = a[i] + (i ? pref[i - 1] : 0);
	}
	cout << solve2(n) << endl;
}
/*
4
2 3 1 7 

5
6 2 3 9 13

3
3 1 2
*/

• Subtask 1: 13 / 13
• Subtask 2: 0 / 14
• Subtask 3: 0 / 10
• Subtask 4: 0 / 36
• Subtask 5: 0 / 27