Submission #139755

#	Time	Username	Problem	Language	Result	Execution time	Memory
139755		ae04071	Circle selection (APIO18_circle_selection)	C++11	19 / 100	3059 ms	35192 KiB

circle_selection

#include <bits/stdc++.h>
#define fi first
#define se second
#define sz(x) ((int)(x).size())
using namespace std;
using pii = pair<int,int>;

const int INF = 1e9;

struct circle{
    int x,y,r,i;
    bool operator<(const circle &rhs)const {
        return r!=rhs.r ? r>rhs.r : i<rhs.i;
    }
    bool touch(circle &rhs)const {
        return 1ll*(x-rhs.x)*(x-rhs.x)+1ll*(y-rhs.y)*(y-rhs.y)<=1ll*(r+rhs.r)*(r+rhs.r);
    }
}arr[300001],o[300001];
int n,chk[300001];

set<pii> tr;

int main() {
    scanf("%d",&n);
    for(int i=1;i<=n;i++) {
        scanf("%d%d%d",&arr[i].x,&arr[i].y,&arr[i].r);
        arr[i].i=i;
        tr.insert({arr[i].x,i});
        o[i] = arr[i];
    }
    sort(o+1, o+n+1);
    //sort(arr+1,arr+n+1);

    for(int i=1;i<=n;i++) {
        int idx = o[i].i;
        if(chk[idx]) continue;
        
        chk[idx] = idx;
        tr.erase({o[i].x,idx});
        
        auto it = tr.lower_bound({max(-2ll*INF, o[i].x-2ll*o[i].r), -1});
        vector<pii> ta;
        for(;it!=tr.end() && it->fi-2ll*o[i].r<=o[i].x;it++) {
            ta.push_back({arr[it->se].y, it->se});
        }
        sort(ta.begin(),ta.end());


        auto jt = lower_bound(ta.begin(),ta.end(),pii(max(-2ll*INF, o[i].y-2ll*o[i].r), -1));
        int v = jt - ta.begin();

        for(int j=v; j<sz(ta) && arr[ta[j].se].y-2ll*o[i].r<=o[i].y;j++) {
            if(o[i].touch(arr[ta[j].se])) {
                chk[ta[j].se] = idx;
                tr.erase({arr[ta[j].se].x, ta[j].se});
            }
        }
    }
    for(int i=1;i<=n;i++) printf("%d ",chk[i]);

    return 0;
}

Compilation message (stderr)

circle_selection.cpp: In function 'int main()':
circle_selection.cpp:24:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
circle_selection.cpp:26:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&arr[i].x,&arr[i].y,&arr[i].r);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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