Submission #586657

#	Time	Username	Problem	Language	Result	Execution time	Memory
586657		Alan	Split the sequence (APIO14_sequence)	C++17	100 / 100	631 ms	81844 KiB

sequence

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
 
ll dp[2][100005], ps[100005];
int p[205][100005];
 
struct line {
	ll idx, m, c;
	ll cal (ll x) {return m*x + c;}
	ld sectx (line l) {return (ld) (l.c-c) / (m-l.m);}
};
 
int main () {
	int n, k, a;
	cin >> n >> k;
	for (int i = 1; i <= n; i++) cin >> a, ps[i] = ps[i-1] + a;
	deque<line> d;
	for (int j = 1; j <= k; j++) {
		d.push_back({0, 0, 0});
		for (int i = 1; i <= n; i++) {
			while ((int) d.size() >= 2 && d.back().cal(ps[i]) <= d.end()[-2].cal(ps[i])) d.pop_back();
			dp[j&1][i] = d.back().cal(ps[i]) + ps[i]*ps[n] - ps[i]*ps[i];
			p[j][i] = d.back().idx;
			line now = {i, ps[i], dp[~j&1][i] - ps[i]*ps[n]};
			while ((int) d.size() >= 2 && ((now.m == d[0].m && now.c >= d[0].c) || now.sectx(d[0]) <= d[0].sectx(d[1]))) d.pop_front();
			d.push_front(now);
		}
		d.clear();
	}
	auto iter = max_element(dp[k&1]+k, dp[k&1]+n+1);
	cout << *iter << "\n";
	vector<int> path {iter-dp[k&1]};
	for (int i = k; i > 0; i--) path.push_back(p[i][path.back()]);
	for (int i = k-1; i >= 0; i--) cout << path[i] << " ";
	cout << "\n";

	return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:34:24: warning: narrowing conversion of '((iter - ((ll*)(& dp[(k & 1)]))) <unknown operator> 8)' from 'long int' to 'int' [-Wnarrowing]
   34 |  vector<int> path {iter-dp[k&1]};
      |                    ~~~~^~~~~~~~
sequence.cpp:34:24: warning: narrowing conversion of '((iter - ((ll*)(& dp[(k & 1)]))) <unknown operator> 8)' from 'long int' to 'int' [-Wnarrowing]

• Subtask 1: 11 / 11
• Subtask 2: 11 / 11
• Subtask 3: 11 / 11
• Subtask 4: 17 / 17
• Subtask 5: 21 / 21
• Subtask 6: 29 / 29