Submission #922260

#	Time	Username	Problem	Language	Result	Execution time	Memory
922260		Baizho	Split the sequence (APIO14_sequence)	C++14	49 / 100	83 ms	131072 KiB

sequence

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
  
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
 
// #pragma GCC optimize("Ofast,unroll-loops,fast-math")
// #pragma GCC target("popcnt")
 
 
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> pll;
 
#define sz size()
#define ff first
#define ss second
#define all(a) a.begin(),a.end()
#define pb push_back
 
const int mod = ll(1e9)+7; //(b + (a%b)) % b (to mod -1%(10^9+7) correctly in c++ its -1 but its suppose to be 10^9+6
const ll MOD = 998244353;  // (a%mod)*(binpow(b,mod-2,mod) = (a/b)%mod
const int N = ll(2e5)+100;
const int M = ll(2e5) + 100;
const long long inf = 5e18;
const long double eps = 1e-15L;
 
ll lcm(ll a, ll b) { return (a / __gcd(a,b))*b; }
 
ll binpow(ll a, ll b, ll m) { ll res=1; a %= m; while(b>0){ if(b&1)res=(res * a) % m; a=(a * a) % m; b/=2; } return res%m;}
 
void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
 
#define int ll
int n, k, a[N];
 
ll pr[N], dp[N];
int last[N][205];
 
struct line {
	ll m, b;
	int id;
};
 
vector<line> vec;
 
ll val(ll x, line a) {
	return x * a.m + a.b;
}
 
bool bad(line a, line b, line c){
    return (b.b - a.b) * (a.m - c.m) >= (c.b - a.b) * (a.m - b.m);
}
 
void add(line a) {
	while(vec.sz >= 2 && bad(vec[vec.sz - 2], vec.back(), a)) {
		vec.pop_back();
	}
	vec.pb(a);
}
 
pair<ll, int> get(ll x) {
	if(vec.size() == 1) return {val(x, vec[0]), vec[0].id};
	int l = 0, r = vec.sz - 2;
	while(l <= r) {
		int mid = (l + r) / 2;
		if(val(x, vec[mid]) <= val(x, vec[mid + 1])) l = mid + 1;
		else r = mid - 1;
	}
	return {val(x, vec[l]), vec[l].id};
}
 
void Baizho() {
	cin>>n>>k;
	for(int i = 1; i <= n; i ++) {
		cin>>a[i];
		pr[i] = pr[i - 1] + a[i];
	}
	for(int i = 0; i <= n; i ++) dp[i] = -inf;
	dp[0] = 0;
	for(int kk = 1; kk <= k; kk ++) {
		add({pr[kk - 1], dp[kk - 1], kk - 1});
		for(int i = kk; i <= n; i ++) {
			// need to find j
			auto got = get(pr[i]);
			if(dp[i] != -inf) add({pr[i], dp[i], i});
			if(got.ff - pr[i] * pr[i] > dp[i]) {
				dp[i] = got.ff - pr[i] * pr[i];
				last[i][kk] = got.ss;
			}
//			for(int j = 0; j < i; j ++) {
//				if(dp[j][kk - 1] == -inf) continue;
////				+ pr[n] * pr[i] - pr[n] * pr[j]
//				if(dp[j][kk - 1] - pr[i] * pr[i] + pr[i] * pr[j] > dp[i][kk]) {
//					dp[i][kk] = dp[j][kk - 1] - pr[i] * pr[i] + pr[i] * pr[j];
//					last[i][kk] = j;
//				}
//			}
		}
		vec.clear();
	}
	ll pos = 0;
	for(int i = k; i <= n; i ++) {
		if(dp[i] + pr[n] * pr[i] > dp[pos] + pr[n] * pr[pos]) {
			pos = i;
		}
	}
	cout<<dp[pos] + pr[n] * pr[pos]<<"\n";
	vector<int> ans;
	while(pos) {
		ans.pb(pos);
		pos = last[pos][k --];
	}
	reverse(all(ans));
	for(auto x : ans) cout<<x<<" ";
	cout<<"\n";
}
 
signed main() {		
// 	Freopen("nondec");
    ios_base::sync_with_stdio(false);   
    cin.tie(0);cout.tie(0); 
//   	precalc();
   	
    int ttt = 1;
//    cin>>ttt;
 
    for(int i=1; i<=ttt; i++) {Baizho(); }
}

Compilation message (stderr)

sequence.cpp: In function 'void Freopen(std::string)':
sequence.cpp:35:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 | void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
      |                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:35:76: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 | void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
      |                                                                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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