Submission #1169875

#	Time	Username	Problem	Language	Result	Execution time	Memory
1169875		mychecksedad	Aliens (IOI16_aliens)	C++20	100 / 100	179 ms	13940 KiB

aliens

/* Author : Mychecksdead  */
#include<bits/stdc++.h>
//#include"aliens.h"
using namespace std;
#define ll long long int
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define pb push_back
#define all(x) x.begin(), x.end()
#define en cout << '\n'
#define ff first
#define ss second
#define pii pair<int,int>
#define vi vector<int>
const int N = 2e5+100, M = 1e5+10, K = 105, MX = 30;
const ll INF = 1e18;

struct P{
  ll m, b, idx, num_k;
  double eval(double x){
    return x*m + b;
  }
};

double intersection(P x, P y){
  return (x.b - y.b) / (double)(y.m - x.m);
}

struct CH{
  vector<P> C;
  int idx=0;
  void insert(ll c, ll m, int id, int numk){
    P x = {m, c, id, numk};
    if(C.size() && C.back().m == x.m && C.back().b < x.b) return;
    while(C.size() && C.back().m == x.m && C.back().b >= x.b) C.pop_back();
    while(C.size() > 1 && (x.eval(intersection(C.back(), C[int(C.size())-2])) <= C.back().eval(intersection(C.back(), C[int(C.size())-2])))) 
      C.pop_back();
    C.pb(x);
    idx=min(idx,int(C.size())-1);
  }
  P get(ll fi){
    while(idx+1<C.size() && C[idx+1].eval(fi) <= C[idx].eval(fi)) ++idx;
    return C[idx];
  }
};


int n, m, k;
array<ll, 2> a[N];
ll go[2*N];
vector<ll> val;

pair<ll, int> f(ll cost){
  CH cht;
  cht.insert(go[0]*go[0], -2*go[0], 0, 0);
  ll ans = INF;
  int num_k = 0;
  
  for(ll i = 1; i <= m; ++i){
    auto p = cht.get(val[i]);
    ll dp = p.eval(val[i]) + val[i] * val[i] + cost;
    ll best = go[p.idx];
    //cout << i << ' ' << j  << ' ' << dp[i][j] << ' ' << best << ' ';
    if(go[i] == MOD){
      if(ans > dp){
        ans = dp;
        num_k = p.num_k + 1;
      }else if(ans == dp) num_k = min(num_k, (int)p.num_k + 1);
    }
    best = max(best, (go[i]));
    if(go[i] < val[i]){
      dp -= (best - val[i]) * (best - val[i]);
      dp += go[i] * go[i];
      cht.insert(dp, -2*go[i], i, p.num_k + 1);
    }else{
      dp += go[i] * go[i];
      cht.insert(dp, -2*go[i], i, p.num_k + 1);
    }
    //cout << i << ' ' << j << ' ' << dp[i][j] << '\n';
  }

  return pair<ll, int>{ans, num_k};
}

ll take_photos(int nn, int mm, int kk, vector<int> r, vi c){
  n=nn,m=mm,k=kk;
  for(int i=0;i<n;++i){ a[i][0]=r[i],a[i][1]=c[i]; }
  
/*void solve(){
  
  cin >> n >> m >> k;
  for(int i = 0; i < n; ++i) cin >> a[i][0] >> a[i][1];
  */
  for(int i = 0; i < n; ++i){
    if(a[i][0] > a[i][1]){
      swap(a[i][0], a[i][1]);
    }
    val.pb(a[i][0]), val.pb(a[i][1]+1);
  }
  val.pb(0);
  sort(all(val));
  val.erase(unique(all(val)), val.end());
  sort(a, a+n, [&](const array<ll,2> &x, const array<ll, 2> &y){
    return array<ll,2>{x[1],x[0]}<array<ll,2>{y[1],y[0]};
  });
  //for(int i = 0; i < n; ++i) cout << a[i][0] << ' ' << a[i][1] << '\n';
  ll mn = MOD;
  int ptr = n - 1;
  m = int(val.size()) - 1;
  for(int i = m; i >= 0; --i){
    while(ptr >= 0 && a[ptr][1] >= val[i]){
      mn = min(mn, a[ptr][0]);
      --ptr;
    }
    go[i] = mn;
  }
  //for(int j = 0; j <= m; ++j) cout << go[j] << ' '; en;
  ll ans = 0;
  ll L = 0, R = 1e12;
  while(L<=R){
    ll m = (L+R)/2;
    auto [cost, num_k] = f(m);
    //cout << cost - num_k * m << ' ' << num_k << ' ' << m << '\n';
    if(num_k >= k){
      ans = m;
      L = m + 1;
    }else{
      R = m - 1;
    }
  }

  auto res = f(ans);
  return res.ff - k * ans;
}
/*
int main(){
  cin.tie(0); ios::sync_with_stdio(0);
  int tt = 1, aa;
  // freopen("in.txt", "r", stdin);
  // freopen("out.txt", "w", stdout);
  while(tt--){
   solve();
  }
  cerr<<"time taken : "<<(float)clock()/CLOCKS_PER_SEC<<" seconds\n";
  return 0;
} */

Compilation message (stderr)

aliens.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
aliens_c.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 40 / 40