Submission #791356

#	Time	Username	Problem	Language	Result	Execution time	Memory
791356		trucmai	Feast (NOI19_feast)	C++17	71 / 100	69 ms	65616 KiB

feast

//i_love_aisukiuwu
#pragma GCC optimize("Ofast,no-stack-protector,fast-math,unroll-loops,tree-vectorize")
#include <bits/stdc++.h>
using namespace std;

#ifdef LOCAL
	#include "/home/trucmai/.vim/tools.h"
	#define debug(x...) cerr << "\e[91m"<<__func__<<":"<<__LINE__<<" [" << #x << "] = ["; _print(x); cerr << "\e[39m" << endl;
	#else
	#define debug(x...)
#endif

void open(){
  if(fopen("i.inp","r")){
    freopen("i.inp","r",stdin);
    freopen("o.out","w",stdout);
  }
}

#define ll long long
#define all(a) (a).begin(), (a).end()
#define vi vector<ll>
#define pi pair<ll,ll>
#define pii pair<ll,pair<ll,ll>>
#define fi first
#define se second
#define gcd __gcd
#define mset(a,v) memset(a, v, sizeof(a))
#define endl '\n'
#define spc " "

const int MN1 = 1e6 + 5,MN2 = 2e3 + 5,LOG = 27;
const ll MOD = 1e9 + 7,INF = 1e9;
ll n,k,a[MN1],dp[MN2][MN2][2];
/*
dp[i][j][k(0\1)] la max sum tai vi tri i,segment j va state k 
k = 0: 
  dp[i][j][0] = max(dp[i-1][j][0],dp[i-1][j][1] + a[j])
k = 1:
  dp[i][j][1] = max(dp[i-1][j-1][0],dp[i-1][j][1] + a[j])
*/
void solve(){
  cin>>n>>k; ll cnt = 0;
  for(ll i = 1;i <= n;++i){
    cin>>a[i];
    if(a[i] < 0) ++cnt;
  }
  if(cnt == 0){
    ll res = 0;
    for(ll i = 1; i <= n;++i) res += a[i]; 
    cout<<res<<endl;
  }
  else if(cnt == 1){
		ll left = 0, right = 0, flag = 0, pos = -1,res = 0;
		for(int i = 1; i <= n; i++){
			if(a[i] < 0){
				pos = i;
				flag = 1;
				continue;
			}
			else if(flag == 0) left += a[i];
			else right += a[i];
		}
    debug(left,right);
		if(k >= 2)	res = left + right;
		else if(k == 1) res = max(max(left,right), left + right + a[pos]);
	  cout<<res<<endl;
  }
  else if(k == 1){
		ll help = 0,res = 0;
		for(int i = 1; i <= n; i++){
			help += a[i];
			if(res < help) res = help;
			if(help < 0)	help = 0;
		}
    cout<<res<<endl;
	}
  else{
    mset(dp,-1);
    auto f=[&](ll i,ll j,bool state,auto &&f)->ll{
      if(i > n || j > k) return 0;
      ll &res = dp[i][j][state]; 
      if(res != -1) return res;
      res = 0; 
      res = max(res,f(i+1,j,1,f) + a[i]);
      if(!state) res = max(res,f(i+1,j,0,f));
      else if(j + 1 < k && state) res = max(res,f(i+1,j+1,0,f)); 
      return res;
    };
    cout<<f(1,0,0,f)<<endl;
  }
}

signed main(){
  cin.tie(0) -> sync_with_stdio(0);
  open();
  ll t = 1; //cin>>t;
  while(t--) solve(); 
  
  #ifdef LOCAL
    cerr << endl << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
  #endif
}

Compilation message (stderr)

feast.cpp: In function 'void open()':
feast.cpp:15:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |     freopen("i.inp","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~
feast.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen("o.out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 0 / 29