Submission #31976

#	Time	Username	Problem	Language	Result	Execution time	Memory
31976		minimario	Split the sequence (APIO14_sequence)	C++14	71 / 100	2000 ms	87568 KiB

sequence

#include <bits/stdc++.h>
using namespace std;

const int MAX = 100005;
typedef long long ll;
typedef pair<ll, ll> pii;


#define f first
#define s second


pii line[MAX];
int orig[MAX];
double hit[MAX];
int ct = 0;

double sect(pii l1, pii l2) {
	// l1.f * x + l1.s = l2.f * x + l2.s
	return (double)(l2.s - l1.s) / (double)(l1.f - l2.f);

}

int ptr = 1;

void add(ll m, ll b, int k) {
	pii l = {m, b};
	// l and line[2] > hit[2]
	while (ct > 1) {
		if (l.f != line[ct].f && sect(l, line[ct]) > hit[ct]) { break; }
		ct--;
	}
	ct++;
	ptr = min(ptr, ct);
	orig[ct] = k;
	line[ct] = l;
	if (ct != 1) { hit[ct] = sect(l, line[ct-1]); }
}

pii eval(ll x) {
	pii l; int ind = -1;
	if (ct == 0) { return {0, 0}; }
	if (ct == 1) { 
		ptr = 1;
		l = line[1]; 
		ind = orig[1];
	}
	else {
		while (hit[ptr] < x && ptr <= ct) { ptr++; }
		ptr--;
		l = line[ptr]; 
		ind = orig[ptr];
	}
	return {(ll)l.f * (ll)x + (ll)l.s, ind};

}

int a[MAX];
ll p[MAX];
ll dp[MAX][2];
int last[MAX][205];
int main() {
	//freopen("a.in", "r", stdin);
	//freopen("a.out", "w", stdout);
	int n, k0; scanf("%d %d", &n, &k0);
	for (int i=1; i<=n; i++) {
		scanf("%d", &a[i]); 
		p[i] = (ll)p[i-1] + (ll)a[i];
	}
	for (int k=1; k<=k0+1; k++) {
		ct = 0;
		for (int i=k-1; i<=n; i++) {
			if (k == 1) { 
				dp[i][k] = 0;
			}
			else {
				add(-p[i], -(ll)dp[i][(k+1)%2]+(ll)p[i]*(ll)p[i], i);
				if (i != k-1) { 
					pii ans = eval(p[i]);
					dp[i][k%2] = -ans.f; 
					last[i][k] = (int)ans.s;
				}
			}
		}
	}
	k0++;
	printf("%lld\n", dp[n][k0%2]);
	while (k0 != 1) {
		int bef = last[n][k0];
		printf("%d ", bef);
		n = bef; k0--;
	}
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:65:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  int n, k0; scanf("%d %d", &n, &k0);
                                    ^
sequence.cpp:67:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i]); 
                     ^

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