Submission #1114369

#	Time	Username	Problem	Language	Result	Execution time	Memory
1114369		VinhLuu	Line Town (CCO23_day1problem3)	C++17	25 / 25	531 ms	65324 KiB

Main

#include <bits/stdc++.h>
#define int long long
#define ll long long
#define all(lpv) lpv.begin(), lpv.end()
#define fi first
#define se second
using namespace std;

typedef pair<int,int> pii;
const int N = 1e6 + 5;
const int oo = 1e16;
const int mod = 1e6 + 3;

int n, a[N], m, zero;

void add(int &x,int y){
  if(x == -1) x = y;
  else x = min(x, y);
}

int bit[N];

void update(int i,int val){
  for(; i <= n; i += i & -i) bit[i] += val;
}

int get(int i){
  int ret = 0;
  for(; i; i -= i & -i) ret += bit[i];
  return ret;
}

namespace AC{

  pair<int,int> save[2][N];

  int g[2][2];

  vector<int> vr[N];

  void solve(){
    int pre = 0, nx = 1;
    g[pre][0] = 0;
    g[pre][1] = -1;
    g[nx][0] = g[nx][1] = -1;
    int sum = 0;
    for(int i = 1; i <= n; i ++) if(a[i] != 0){
      vr[abs(a[i])].push_back(i);
    }

    int ans = -1;

    for(int val = m; val >= 1; val --){
//      cerr << val << " r\n";
//      for(auto i : vr[val]) cerr << i << " ";
//      cerr << " h\n";
      for(int t = 0; t <= 1; t ++) if(g[pre][t] != -1){
        int ble = t, bri = (sum - t) % 2;

//        cerr << val << " " << t << " " << g[pre][t] << " " << ble << " " << bri  << " start\n";

        deque<int> col[2], rev[2];

        for(auto i : vr[val]){
          if(i & 1){
            if(a[i] > 0) col[0].push_back(i);
            else col[1].push_back(i);
          }else{
            if(a[i] > 0) col[1].push_back(i);
            else col[0].push_back(i);
          }
          if((n - i + 1) & 1){
            if(a[i] > 0) rev[0].push_back(i);
            else rev[1].push_back(i);
          }else{
            if(a[i] > 0) rev[1].push_back(i);
            else rev[0].push_back(i);
          }
        }

        int le = 0, ri = 0;

        int tmp = (int)vr[val].size();

        int ret = 0;

        while(le < tmp){
          int nxt = ((ble + le + 1) & 1);
          if(col[nxt].empty()) break;
          le++;
          int x = col[nxt].front();
          ret += x - 1 - get(x - 1);
          update(x, 1);
          if((n - x + 1) & 1){
            if(a[x] > 0) rev[0].pop_front();
            else rev[1].pop_front();
          }else{
            if(a[x] > 0) rev[1].pop_front();
            else rev[0].pop_front();
          }
          save[0][le] = {nxt, x};
          col[nxt].pop_front();
        }

//        cerr << le << " " << ret << " h\n";

        while(ri < tmp - le){
          int nxt = (((bri + ri + 1) & 1) ^ 1);
          if(rev[nxt].empty()) break;
          ri++;
          int x = rev[nxt].back();
          ret += n - x - (get(n) - get(x));
          update(x, 1);
          save[1][ri] = {nxt, x};
          rev[nxt].pop_back();
        }

        while(le >= 0){
          if(le + ri == tmp) add(g[nx][(ble + le) % 2], ret + g[pre][t]);
          if(!le) break;
          int nxt, x; tie(nxt, x) = save[0][le];
          col[nxt].push_front(x);
          update(x, -1);
          ret -= x - 1 - get(x - 1);
          if((n - x + 1) & 1){
            if(a[x] > 0) rev[0].push_front(x);
            else rev[1].push_front(x);
          }else{
            if(a[x] > 0) rev[1].push_front(x);
            else rev[0].push_front(x);
          }
          le--;
          while(ri < tmp - le){
            int _right = (((bri + ri + 1) & 1) ^ 1);
            if(rev[_right].empty()) break;
            int pos = rev[_right].back();
            ri++;
            ret += (n - pos - (get(n) - get(pos)));
            update(pos, 1);
            save[1][ri] = {nxt, pos};
            rev[_right].pop_back();
          }
        }
        while(ri > 0){
          int nxt, x; tie(nxt, x) = save[1][ri];
          update(x, -1);
          ri--;
        }
        g[pre][t] = -1;
      }

      sum += (int)vr[val].size();
      for(auto i : vr[val]) update(i, 1);

      if(g[nx][0] == -1 && g[nx][1] == -1){
        cout << -1;
        return;
      }
      swap(pre, nx);
    }
    if(g[pre][0] != -1) add(ans, g[pre][0]);
    if(g[pre][1] != -1) add(ans, g[pre][1]);
    cout << ans;
  }
}

signed main(){
  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  #define task "v"
  if(fopen(task ".inp","r")){
    freopen(task ".inp","r",stdin);
    freopen(task ".out","w",stdout);
  }
  cin >> n;
  vector<int> rrh;
  for(int i = 1; i <= n; i ++){
    cin >> a[i];
    zero += (a[i] == 0);
    if(a[i] != 0) rrh.push_back(abs(a[i]));
  }
  sort(all(rrh)); rrh.resize(unique(all(rrh)) - rrh.begin());
  m = (int)rrh.size();
  for(int i = 1; i <= n; i ++){
    if(a[i] == 0) continue;
    if(a[i] < 0) a[i] = -(lower_bound(all(rrh), abs(a[i])) - rrh.begin() + 1);
    else a[i] = lower_bound(all(rrh), abs(a[i])) - rrh.begin() + 1;
  }
  AC :: solve();
}
/*
5
0 -1 -1 0 1
*/

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:171:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  171 |     freopen(task ".inp","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:172:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  172 |     freopen(task ".out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 3 / 3
• Subtask 2: 3 / 3
• Subtask 3: 3 / 3
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 3 / 3
• Subtask 7: 2 / 2
• Subtask 8: 3 / 3