Topic link: https: //vjudge.net/problem/POJ-3714
Meaning of the questions: Given two set points, for the shortest distance.
Ideas: the nearest point on the plane on the basis added a condition, what I do not visit marked with f, f 1 is a collection of 1, f 2 of the set to -1, then find the distance between two points, if af * calculating the distance bf = -1, or if the product is returned inf 1. And on the other hdoj1007 same.
AC Code:
#include<cstdio> #include<algorithm> #include<cmath> #include<cstdlib> using namespace std; const int maxn=2e5+5; const double inf=1e30; int T,n,cnt,id[maxn]; struct node{ int x,y,f; }pt[maxn]; bool operator < (const node& a,const node& b){ if(a.x==b.x) return a.y<b.y; return a.x<b.x; } bool cmp(int a,int b){ return pt[a].y<pt[b].y; } double dist(const node& a,const node& b){ if(a.f*b.f==1) return inf; return sqrt(1.0*(a.x-b.x)*(a.x-b.x)+1.0*(a.y-b.y)*(a.y-b.y)); } double fenzhi(int l,int r){ double d=inf; if(l==r) return d; if(l+1==r) return dist(pt[l],pt[r]); int mid=(l+r)>>1; d=min(fenzhi(l,mid),fenzhi(mid+1,r)); cnt=0; int t1,t2,l1=l,r1=mid,mid1; while(l1<=r1){ mid1=(l1+r1)>>1; if(pt[mid].x-pt[mid1].x<d) r1=mid1-1; else l1=mid1+1; } t1=l1; l1=mid+1,r1=r; while(l1<=r1){ mid1=(l1+r1)>>1; if(pt[mid1].x-pt[mid].x<d) l1=mid1+1; else r1=mid1-1; } t2=r1; for(int i=t1;i<=t2;++i) id[++cnt]=i; sort(id+1,id+cnt+1,cmp); for(int i=1;i<cnt;++i) for(int j=i+1;j<=cnt&&(pt[id[j]].y-pt[id[i]].y<d);++j) d=min(d,dist(pt[id[i]],pt[id[j]])); return d; } int main(){ scanf("%d",&T); while(T--){ scanf("%d",&n); for(int i=1;i<=2*n;++i){ scanf("%d%d",&pt[i].x,&pt[i].y); if(i<=n) pt[i].f=1; else pt[i].f=-1; } sort(pt+1,pt+1+2*n); printf("%.3f\n",fenzhi(1,2*n)); } return 0; }