平面最近点对模板[luogu P1429]

 %:pragma GCC optimize()
 #include<bits/stdc++.h>
 #define DB double
 #define m (((l)+(r))>>1)
 #define sqr(x) ((x)*(x))
 using namespace std;
 ;
 int n,tot; DB ans;
 struct point {DB x,y;}a[N],now[N];
 inline DB dis(point u,point v) {return sqrt(sqr(u.x-v.x)+sqr(u.y-v.y));}
 inline bool cmp(point u,point v) {return u.x==v.x?u.y<v.y:u.x<v.x;}
 inline bool cmp0(point u,point v) {return u.y<v.y;}
 DB solve(int l,int r) {
     ==r) return dis(a[l],a[r]);
     DB ret=min(solve(l,m),solve(m+,r)); ;
     for (int i=l; i<=r; i++) if (fabs(a[i].x-a[m].x)<ret) now[++k]=a[i];
     sort(now+,now++k,cmp0);
     ; i<k; i++)
         ; j<=k&&now[j].y-now[i].y<ret; j++) ret=min(ret,dis(now[i],now[j]));
     return ret;
 }
 int main() {
     scanf("%d",&n);
     ; i<=n; i++) scanf("%lf%lf",&a[i].x,&a[i].y);
     ) ; else
     ) ],a[])),;
     sort(a+,a++n,cmp);
     printf(,n));
     ;
 }