Submission #42040

#	Time	Username	Problem	Language	Result	Execution time	Memory
42040		OneSubmissionMan	Beads and wires (APIO14_beads)	C++11	0 / 100	2 ms	356 KiB

beads

# include <bits/stdc++.h>

# define F first
# define S second
# define mp make_pair
// everything go according to my plan
# define pb push_back
# define sz(a) (int)(a.size())
# define vec vector
// shimkenttin kyzdary, dzyn, dzyn, dzyn...
# define y1    Y_U_NO_y1
# define left  Y_U_NO_left
# define right Y_U_NO_right

using namespace std;

typedef pair <int, int> pii;
typedef long long ll;
typedef long double ld;

const int Mod = (int)1e9 + 7;
const int MX = 1073741822;
const ll MXLL = 4e18;
const int Sz = 1110111;
// a pinch of soul
inline void Read_rap () {
  ios_base :: sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
}
inline void randomizer3000 () {
  unsigned int seed;
  asm ("rdtsc" : "=A"(seed));
  srand (seed);
}
void files (string problem) {
  if (fopen ((problem + ".in").c_str(),"r")) {
    freopen ((problem + ".in").c_str(),"r",stdin);
    freopen ((problem + ".out").c_str(),"w",stdout);
  }
}
void localInput (string in = "s") {
  if (fopen (in.c_str(), "r"))
    freopen (in.c_str(), "r", stdin);
  else {
    cerr << "Input file not found" << endl;
  }
}    
const int K = 200 + 1;
const int N = 1e5 + 1;

int n;
int k;

ll pref[Sz];

int a[Sz];
             
int pr[K][N];

const double eps = 1e-12;

struct CHT {
  struct line {
    ll k, b;      
    ll get (ll x) {
      return k * x + b;
    }
  };
  vec<line> r;
  vec<int> id;
  int ptr;

  CHT() : ptr(0) {}
  void clear() {
    r.clear();
    id.clear();
    ptr = 0;
  }  
  ld intersection (line &a, line &b) {
    return ((ld)b.b - a.b) / ((ld)a.k - b.k);
  }       
  void add_line (line last, int Id) {
    while (sz(r) >= 2 && intersection (r[sz(r) - 2], r[sz(r) - 1]) > intersection (r[sz(r)-2], last)) {
      r.pop_back();
      id.pop_back();
    } 
    r.pb (last);
    id.pb (Id);
  }
  pair <ll, int> get2 (ll x, vec<line> &a) {
    int l = 0, r = sz(a)-2, ans = sz(a)-1;
    while (l <= r) {
      int mid = (l+r) >> 1;
      if (intersection (a[mid], a[mid + 1]) >= x)
        r = mid-1, ans = mid;
      else
        l = mid+1;
    }             
    return {a[ans].get(x), id[ans]};
  }  
  pair <ll, int> get (ll x) {   
    ptr = min (ptr, sz(r) - 1);
    while (ptr + 1 < sz(r) && intersection (r[ptr], r[ptr + 1]) < x)
      ptr++;
    return get2 (x, r);        
    return {r[ptr].get (x), id[ptr]};
  }
  void show() {   
    cout << endl;
    for (int i = 0; i < sz(r); i++) 
      cout << r[i].k << ' ' << r[i].b << "  ";
    cout << endl;
    cout << "X: ";
    for (int i = 0; i < sz(r) - 1; i++)
      cout << intersection (r[i], r[i + 1]) << ' ';
    cout << endl;
  }
};

int main()
{
  Read_rap();
  //localInput();
  cin >> n >> k;   
  for (int i = 1; i <= n; i++)
    cin >> a[i];

  for (int i = 1; i <= n; i++)
    pref[i] = pref[i - 1] + a[i]; 
  
  ll dp[n + 2] = {0}, nw[n + 2] = {0};
  CHT T;
  for (int i = 1; i <= k; i++) {
    T.clear();
    for (int j = i + 1; j <= n; j++) {
      if (j > i + 1 && pref[j] == pref[j - 1]) {
        nw[j] = nw[j - 1];
        pr[i][j] = pr[i][j - 1];
        continue;
      }    
      j--;
      T.add_line ( {pref[j], -pref[j] * pref[j] + dp[j]}, j);
      j++;
      tie (nw[j], pr[i][j]) = T.get (pref[j]); 
    }            
    //T.show();

    for (int j = 1; j <= n; j++)
      dp[j] = nw[j];  
  }
  cout << dp[n] << endl;

  for (int i = k, j = n; i >= 1; ) {
    j = pr[i][j]; 
    i--;     
    assert (j);
    cout << j << ' ';
  }
  return 0;
}










// Coded by Z..

Compilation message (stderr)

beads.cpp: In function 'void files(std::__cxx11::string)':
beads.cpp:37:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     freopen ((problem + ".in").c_str(),"r",stdin);
     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
beads.cpp:38:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     freopen ((problem + ".out").c_str(),"w",stdout);
     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
beads.cpp: In function 'void localInput(std::__cxx11::string)':
beads.cpp:43:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     freopen (in.c_str(), "r", stdin);
     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43