LA 3270 - Simplified GSM Network

来源：互联网发布：京东数据分析笔试编辑：程序博客网时间：2024/04/25 12:50

还是觉得应该先把论文刷完

感觉好像掌握了构造维诺图的特殊技巧

论文的方法真是奥妙重重

但是时间复杂度怎么算，我有点方

O(ans)?

#include<iostream>#include<cstring>#include<cstdio>#include<cmath>#include<queue>#define sqr(x) ((x)*(x))using namespace std;const int inf=1e9;struct point{double x,y;}b[55],c[55];int B,C;struct Edge{int to,next,v;}e[20005];int head[55],cnt;void ins(int u,int v,int w){e[++cnt]=(Edge){v,head[u],w};head[u]=cnt;}void insert(int u,int v,int w){ins(u,v,w);ins(v,u,w);}point getmid(point a,point b){return (point){(a.x+b.x)*0.5,(a.y+b.y)*0.5};}double dist(point a,point b){return sqrt(sqr(a.x-b.x)+sqr(a.y-b.y));}int belong(point a){double ans=1e60;int p;for(int i=1;i<=B;i++)if(dist(a,b[i])<ans)ans=dist(a,b[i]),p=i;return p;}int calc(point a,point b){if(belong(a)==belong(b))return 0;if(dist(a,b)<1e-6)return 1;return calc(a,getmid(a,b))+calc(getmid(a,b),b);}int d[55];bool inq[55];void spfa(int s){memset(d,0x3f,sizeof(d));d[s]=0;queue<int>q;q.push(s);while(!q.empty()){int u=q.front();q.pop();inq[u]=0;for(int i=head[u];i;i=e[i].next){int v=e[i].to;if(d[v]>d[u]+e[i].v){d[v]=d[u]+e[i].v;if(!inq[v]){inq[v]=1;q.push(v);}}}}}int main(){//freopen("a.in","r",stdin);int R,Q,kase=0;while(scanf("%d%d%d%d",&B,&C,&R,&Q)&&B){for(int i=1;i<=B;i++)scanf("%lf%lf",&b[i].x,&b[i].y);for(int i=1;i<=C;i++)scanf("%lf%lf",&c[i].x,&c[i].y);memset(head,0,sizeof(head));cnt=0;while(R--){int u,v;scanf("%d%d",&u,&v);insert(u,v,calc(c[u],c[v]));}printf("Case %d:\n",++kase);while(Q--){int s,t;scanf("%d%d",&s,&t);spfa(s);if(d[t]>inf)puts("Impossible");else printf("%d\n",d[t]);}}return 0;}

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