Submission #43703

#	Time	Username	Problem	Language	Result	Execution time	Memory
43703		baactree	Split the sequence (APIO14_sequence)	C++14	0 / 100	861 ms	83448 KiB

sequence

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n, k;
ll dp[2][100005];
int par[205][100005];
ll sum[100005];
int arr[100005];
pair<ll, ll> dd[100005];
double calc(pair<ll, ll> a, pair<ll, ll> b) {
	return ((double)a.second - b.second) / (b.first - a.first);
}
int main() {
	scanf("%d%d", &n, &k);
	for (int i = 1; i <= n; i++) {
		scanf("%d", &arr[i]);
		sum[i] = sum[i - 1] + arr[i];
	}
	for (int i = 1; i <= k; i++) {
		deque<int> dq;
		int cur = i & 1;
		int pre = (i - 1) & 1;
		for (int j = 2; j <= n; j++) {
			if (sum[j - 1] == sum[j - 2]) {
				dp[cur][j] = dp[pre][j - 1];
				par[i][j] = j - 1;
				continue;
			}
			ll a = sum[j - 1];
			ll b = dp[pre][j - 1] - sum[j - 1] * sum[j - 1];
			dd[j - 1] = make_pair(a, b);
			while (dq.size() > 1 && calc(dd[dq.back()], dd[j-1]) <= calc(dd[dq[dq.size() - 2]], dd[j-1]))
				dq.pop_back();
			dq.push_back(j-1);
			while (dq.size() > 1 && calc(dd[dq[0]], dd[dq[1]]) <= sum[j]) 
				dq.pop_front();
			dp[cur][j] = dd[dq[0]].first * sum[j] + dd[dq[0]].second;
			par[i][j] = dq[0];
		}
	}
	printf("%lld\n", dp[k&1][n]);
	while (k) {
		printf("%d ", par[k][n]);
		n = par[k][n];
		k--;
	}
	printf("\n");
	return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:14:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &k);
                       ^
sequence.cpp:16:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &arr[i]);
                       ^

• Subtask 1: 0 / 11
• Subtask 2: 0 / 11
• Subtask 3: 0 / 11
• Subtask 4: 0 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29