Submission #156823

#	Time	Username	Problem	Language	Result	Execution time	Memory
156823		jhnah917	Split the sequence (APIO14_sequence)	C++14	100 / 100	469 ms	85500 KiB

sequence

#include <bits/stdc++.h>
#define x first
#define y second
#define all(v) v.begin(), v.end()
using namespace std;
 
typedef long long ll;
typedef pair<ll, ll> p;
 
struct CHT{
	ll a[101010], b[101010], c[101010];
	int pv, top;
	
	void init(){
		pv = top = 0;
	}
	
	ll f(ll idx, ll x){
		return a[idx]*x + b[idx];
	}
	
	void insert(ll aa, ll bb, ll cc){
		if(top >= 1 && aa == a[top-1]){
			c[top-1] = cc; return;
		}
		while(top >= 2 && (b[top-1] - b[top-2]) * (a[top-2] - aa) >= (bb - b[top-2]) * (a[top-2] - a[top-1])) top--;
		a[top] = aa;
		b[top] = bb;
		c[top] = cc;
		top++;
		if(pv >= top) pv = top - 1;
	}
	
	p get(ll x){
		while(pv+1 < top && a[pv+1]*x + b[pv+1] > a[pv]*x + b[pv]) pv++;
		return {f(pv, x), c[pv]};
	}
} cht;
 
ll arr[101010];
ll sum[101010];
ll dp[2][101010];
int track[222][101010];
vector<int> ans;
 
int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	int n, k; cin >> n >> k;
	for(int i=1; i<=n; i++) cin >> arr[i], sum[i] = sum[i-1] + arr[i];
	
	for(int i=1; i<=k; i++){
		cht.init();
		cht.insert(0, 0, 0);
		for(int j=1; j<=n; j++){
			auto now = cht.get(sum[j]);
			dp[i&1][j] = now.x;
			track[i][j] = now.y;
			cht.insert(sum[j], dp[i-1&1][j] - sum[j] * sum[j], j);
		}
	}
	cout << dp[k&1][n] << "\n";
	
	int now = n;
	ans.push_back(-1);
	for(int i=k; i>=1; i--){
		ans.push_back(track[i][now]);
		now = track[i][now];
	}
	sort(all(ans));
	for(int i=1; i<=k; i++){
		if(!ans[i]) ans[i] = 1;
		if(ans[i] <= ans[i-1]) ans[i] = ans[i-1] + 1;
	}
	for(int i=1; i<=k; i++) cout << ans[i] << " ";
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:58:27: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
    cht.insert(sum[j], dp[i-1&1][j] - sum[j] * sum[j], j);
                          ~^~

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