Submission #557473

#	Time	Username	Problem	Language	Result	Execution time	Memory
557473		600Mihnea	Road Construction (JOI21_road_construction)	C++17	100 / 100	3170 ms	18356 KiB

road_construction

#include <bits/stdc++.h>

bool home = 1;

using namespace std;

typedef long long ll;
const int N=250000+7;

struct T{
  ll x;
  ll y;
  int y_norm;
};

bool cmpTx(T a,T b) {
  return a.x<b.x;
}

int n;
int k;
T a[N];
vector<ll> ys;

int aib[N];

void clr() {
  for(int i=1;i<=n;i++) aib[i]=0;
}

void add(int i,int x) {
  while (i<=n) {
    aib[i]+=x;
    i+=i&(-i);
  }
}

int get(ll val) {
  int low=0,high=(int)ys.size()-1,i=0,sol=0;
  while (low<=high) {
    int mid=(low+high)/2;
    if(ys[mid]<=val) {
      i=mid+1;
      low=mid+1;
    }else{
      high=mid-1;
    }
  }
  while(i) {
    sol+=aib[i];
    i-=i&(-i);
  }
  return sol;
}

ll how_many_under(ll d) {
  clr();
  ll sol=0;
  int pt=1;
  for (int i=1;i<=n;i++) {
    while (a[i].x-a[pt].x>d) add(a[pt++].y_norm,-1);
    sol+=get(a[i].y+d)-get(a[i].y-d-1);
    add(a[i].y_norm,+1);
  }
  return sol;
}

signed main() {
#ifdef ONLINE_JUDGE
  home = 0;
#endif

  home=0;

  if (home) {
    freopen("I_am_iron_man", "r", stdin);
  }
  else {
    ios::sync_with_stdio(0); cin.tie(0);
  }


  cin>>n>>k;

  for (int i=1;i<=n;i++) {
    int x,y;
    cin>>x>>y;
    a[i].x=x+y;
    a[i].y=x-y;
    ys.push_back(a[i].y);
  }
  sort(ys.begin(), ys.end());
  ys.resize(unique(ys.begin(),ys.end())-ys.begin());

  for (int i=1;i<=n;i++) {
    a[i].y_norm=lower_bound(ys.begin(),ys.end(),a[i].y)-ys.begin()+1;
  }

  sort(a+1,a+n+1,cmpTx);

  ll low=0,high=(ll)1e10,sol=-1;

  while (low<=high) {
    ll mid=(low+high)/2;
    if(how_many_under(mid)<=k) {
      sol=mid;
      low=mid+1;
    }else{
      high=mid-1;
    }
  }
  vector<ll> v;
  multiset<pair<ll, int>> s;
  int pt=1;

  for (int i=1;i<=n;i++) {
    while (a[i].x-a[pt].x>sol) s.erase(s.find({a[pt].y, pt++}));


    ll low=a[i].y-sol;
    ll high=a[i].y+sol;

    auto it=s.lower_bound({low, -1});

    while (it!=s.end()&&it->first<=high) {
      int j=it->second;
      v.push_back(max(a[i].x-a[j].x,abs(a[i].y-a[j].y)));
      it++;
    }

    s.insert({a[i].y, i});
  }
  sort(v.begin(),v.end());
  assert((int)v.size()<=k);
  v.resize(k, sol+1);
  for (auto &x: v) {
    cout<<x<<"\n";
  }
}

Compilation message (stderr)

road_construction.cpp: In function 'int main()':
road_construction.cpp:117:59: warning: operation on 'pt' may be undefined [-Wsequence-point]
  117 |     while (a[i].x-a[pt].x>sol) s.erase(s.find({a[pt].y, pt++}));
      |                                                         ~~^~
road_construction.cpp:76:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |     freopen("I_am_iron_man", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 6 / 6
• Subtask 3: 7 / 7
• Subtask 4: 20 / 20
• Subtask 5: 27 / 27
• Subtask 6: 35 / 35