Submission #508208

#	Time	Username	Problem	Language	Result	Execution time	Memory
508208		oneloveforever	Circle selection (APIO18_circle_selection)	C++14	0 / 100	947 ms	42260 KiB

circle_selection

#include<bits/stdc++.h>

using namespace std;

#define ll      long long
#define pb      push_back
#define sz(x)   x.size()

const int   N   = 3e5 + 1;
const int   inf = 1e9 + 7;

typedef vector<int> vi;

struct  Circle  {
    int x, y;
    int R, i;
    int ans;
}   C[N];
bool Share(Circle a,Circle b)   {
    double need=sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
    return need<=a.R+b.R;
}

ll  encode(int x,int y) {   return  ((ll)x << 31) + y;  }

int main()  {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int n;  cin >> n;

    for(int i = 0 ; i < n ; ++i)    {
        cin >> C[i].x;  C[i].x += inf;
        cin >> C[i].y;  C[i].y += inf;
        cin >> C[i].R;
        C[i].i = i;
        C[i].ans = -1;
    }

    sort(C,C + n,[&](Circle C1,Circle C2)   {
         if (C1.R != C2.R)  return  C1.R > C2.R;
         if (C1.R == C2.R)  return  C1.i < C2.i;
    });
    int unit = 2e9 + 1;

    unordered_map<ll,vi>    Combi;

    auto build = [&]()  {
        Combi.clear();
        for(int i = 0 ; i < n ; ++i)    if (C[i].ans < 0)   {
            int x = C[i].x / unit;
            int y = C[i].y / unit;

            Combi[encode(x,y)].pb(i);
        }
    };

    for(int i = 0 ; i < n ; ++i)    if (C[i].ans < 0)   {
        //cout << C[i].i << " ";
        if (unit > C[i].R * 2)  {
            unit = C[i].R;
            build();
        }
        int x = C[i].x / unit;
        int y = C[i].y / unit;

        for(int a = x - 2 ; a < x + 3 ; ++a)
        for(int b = y - 2 ; b < y + 3 ; ++b)    {
            ll  Hash = encode(a,b);

            if(!Combi.count(Hash))
                continue;

            vi &v = Combi[Hash];

            for(int j = 0 ; j < v.size() ; ++j) if (Share(C[i],C[v[j]]))    {
                C[v[j]].ans = C[i].i;

                swap(v[j],v.back());
                v.pop_back();
                j--;
            }
        }
    }
    sort(C,C + n,[&](Circle C1,Circle C2)   {   return  C1.i < C2.i;    });

    for(int i = 0 ; i < n ; ++i)
        cout << C[i].ans + 1 << " ";
}

Compilation message (stderr)

circle_selection.cpp: In function 'int main()':
circle_selection.cpp:76:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   76 |             for(int j = 0 ; j < v.size() ; ++j) if (Share(C[i],C[v[j]]))    {
      |                             ~~^~~~~~~~~~
circle_selection.cpp: In lambda function:
circle_selection.cpp:43:5: warning: control reaches end of non-void function [-Wreturn-type]
   43 |     });
      |     ^

• Subtask 1: 0 / 7
• Subtask 2: 0 / 12
• Subtask 3: 0 / 15
• Subtask 4: 0 / 23
• Subtask 5: 0 / 30
• Subtask 6: 0 / 13