Submission #199407

#	Time	Username	Problem	Language	Result	Execution time	Memory
199407		mrtsima22	Split the sequence (APIO14_sequence)	C++17	100 / 100	1501 ms	81940 KiB

sequence

#pragma GCC optimize "-O3"
#pragma GCC optimize("Ofast")
#pragma GCC optimization ("unroll-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define NumberOfOnes __builtin_popcount
#define LSOne(S) (S & (-S))
#define ll long long
#define two pair<ll,ll>
#define twoll pair<ll,ll>
#define four pair<two,two>
#define pb push_back
#define eb emplace_back
#define mk make_pair
#define y1 y1922
#define INF 1000000000000000000
#define P 1000000007
#define lmax 1000000000
#define nn 1000003
#define ff first.first
#define fs first.second
#define sf second.first
#define ss second.second
#define f first
#define s second
#define vi vector<ll>
#define vll vector<ll>
#define vtwo vector<two>
#define ALL(container) (container).begin(), (container).end()
#define sz(container) (ll)(container.size())
#define max(a,b) ((a)>(b)?(a):(b))
#define min(a,b) ((a)<(b)?(a):(b))
#define mid(a,b) (a+b>>1)
#define minN 0
#define maxN 10000000
#define na(x) ((x)<P?(x):(x)-P)
#define ab(a) (-(a)<(a)?(a):-(a))
#define FAST std::ios::sync_with_stdio(false)
#define xRand mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define rnd rng
#define IT iterator
typedef
tree<
  ll,// aq pair<ll,ll> shegidzlia
  null_type,
  less/*_equal*/<ll>,// aqac
  rb_tree_tag,
  tree_order_statistics_node_update>
ordered_set;
// '_equal' mashin ginda roca multiset gchirdeba
template<class key, class value,class cmp = std::less<key>>
using ordered_map = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;
ordered_map<ll, ll> my_map;
inline ll rin(){
	ll x=0,w=1;char ch=getchar();
	while ((ch<'0'||ch>'9')&&ch!='-') ch=getchar();
	if (ch=='-') w=0,ch=getchar();
	while (ch>='0'&&ch<='9') x=(x<<3)+(x<<1)+ch-'0',ch=getchar();
	return w?x:-x;
}
inline ll bin(){
	ll x=0;char ch=getchar();
	while (ch<'0'||ch>'9') ch=getchar();
	while (ch>='0'&&ch<='9') x=(x<<3)+(x<<1)+ch-'0',ch=getchar();
	return x;
}
int v;
ll n,k,a[100003],pref[100003],dp[2][100003];
int p[220][100003];
ll f(int l,int r,int k){
	ll a=pref[k]-pref[l-1];
	ll b=pref[r]-pref[k];
	return a*b;
}
void solve(int l,int r,int optl,int optr){
	if(l>r)
		return;
//	cout<<l<<" "<<r<<" "<<optl<<" "<<optr<<" "<<v<<endl;
	int t=v&1;
	int mid=l+r>>1;
	twoll opt={-INF,-1};
	for(int i=optl;i<=min(mid-1,optr);i++){
		opt=max(opt,mk((ll)dp[t^1][i]+f(i+1,n,mid),(ll)i));
	}
	dp[t][mid]=opt.f;
	p[v][mid]=opt.s;
 
	solve(l,mid-1,optl,opt.s);
	solve(mid+1,r,opt.s,optr);
}
void bt(int k, int n){
	if(!k) return;
	cout<<n<<" ";
	bt(k-1,p[k][n]);
}
int main(){FAST;xRand;
cin>>n>>k;
for(int i=1;i<=n;i++){
	cin>>a[i]; 
	pref[i]=pref[i-1]+a[i];
}
for(int i=1;i<=k;i++){
	v=i;
	solve(1,n,0,n);
}
int g=k;
for(int i=1;i<n;i++)
	if(dp[k&1][i]>=dp[k&1][g])
		g=i;
cout<<dp[k&1][g]<<endl;
bt(k,g);

	// you should actually read the stuff at the bottom
}//                     
/*

7 3
4 1 3 4 0 2 3

*/
/* stuff you should look for
	* ll overflow, array bounds
	* special cases (n=1?), slow multiset operations
	* do smth instead of nothing and stay organized
	* unordered_map, hash_map, scanf, calculate answer instead of ans*K
*/
/*
for(ll i=1;i<=n;i++){
	for(ll j=1;j<=k;j++){
		for(ll o=0;o<i;o++){
			x=(sm[i]-sm[o])*(sm[n]-sm[i])+
			dp[o][j-1];

//			sm[i]*sm[n]-sm[i]*sm[i]-(sm[n]-sm[i])*sm[o]+dp[o][j-1];
//			A          -B          -C*sm[o]+dp[o][j-1]

			if(x>=dp[i][j]){
				dp[i][j]=x;
				p[i][j]=o;
			}
		}
	}
}
*/
//			https://cp-algorithms.com/geometry/convex_hull_trick.html
//			https://cp-algorithms.com/dynamic_programming/divide-and-conquer-dp.html

/*


                   *         *
                  * *       * *
                 *   *     *   *
                *     *   *     *
                 *   *   * *   *
                  *   *   *   *
                   *   * *   *
                     *  *   *
					   *  *


*/

Compilation message (stderr)

sequence.cpp:3:0: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
 #pragma GCC optimization ("unroll-loops")
 
sequence.cpp: In function 'void solve(int, int, int, int)':
sequence.cpp:82:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=l+r>>1;
          ~^~

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