Problem I
Teen Girl Squad
Input: Standard Input
Output: Standard Output
Time limit: 3.000 seconds
-- 3 spring rolls please. |
Strong Bad
You are part of a group of n teenage girls armed with cellphones. You have some news you want to tell everyone in the group. The problem is that no two of you are in the same room, and you must communicate using only cellphones. What's worse is that due to excessive usage, your parents have refused to pay yourcellphone bills, so you must distribute the news by calling each other in the cheapest possible way. You will call several of your friends, they will call some of their friends, and so on until everyone in the group hears the news.
Each of you is using a different phone service provider, and you know the price of girl A calling girl B for all possible A and B. Not all of your friends like each other, and some of them will never call people they don't like. Your job is to find the cheapest possible sequence of calls so that the news spreads from you to all n-1 other members of the group.
The first line of input gives the number of cases, N (N<150). N test cases follow. Each one starts with two lines containing n (0<= n<=1000) and m (0 <= m <= 40,000) . Girls are numbered from 0 to n-1 , and you are girl 0. The next m lines will each contain 3 integers, u, v and w, meaning that a call from girl u to girl v costs w cents (0 <= w <= 1000) . No other calls are possible because of grudges, rivalries and because they are, like, lame. The input file size is around 1200 KB.
For each test case, output one line containing "Case #x:" followed by the cost of the cheapest method of distributing the news. If there is no solution, print "Possums!" instead.
4 2 1 0 1 10 2 1 1 0 10 4 4 0 1 10 0 2 10 1 3 20 2 3 30 4 4 0 1 10 1 2 20 2 0 30 2 3 100 |
Case #1: 10 Case #2: Possums! Case #3: 40 Case #4: 130 |
Problem setter: Igor Naverniouk
题目:http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=65&page=show_problem&problem=2124
分析:这题也是最小树形图,而且边的权值范围不大,继续用基数排序优化,这个复杂度,又刷到Rank1.。。。
留念~~~
Ranking | Submission | User | Run Time | Language | Submission Date |
1 | 9224799 | Pira | 0.028 | C++ | 2011-09-05 06:05:29 |
代码:
#include<cstdio> using namespace std; const int mm=44444; const int mn=1111; struct edge { int s,t,w; }g[mm],h[mm]; int head[mm],next[mm]; int p[mn],q[mn],mark[mn],fp[mn],from[mn],vis[mn],in[mn],w[mn],ans,sum; int i,j,k,n,m,e,r,mw,t,cas=0; bool huan; inline void addedge(int u,int v,double c) { g[e].s=u,g[e].t=v,g[e].w=c,next[e]=head[u],head[u]=e++; if(c>mw)mw=c; } void dfs(int u) { ++sum,vis[u]=1; for(int i=head[u];i>=0;i=next[i]) if(!vis[g[i].t])dfs(g[i].t); } inline void init(int& a) { char ch=getchar(); while (ch<'0'||ch>'9') ch=getchar(); for (a=0; ch>='0'&&ch<='9'; ch=getchar()) a=a*10+ch-48; } void mysort() { int i; for(i=0;i<=n;++i)q[i]=0; for(i=0;i<=mw;++i)p[i]=0; for(i=0;i<e;++i)++q[g[i].t],++p[g[i].w]; for(i=1;i<=n;++i)q[i]+=q[i-1]; for(i=n;i>0;--i)q[i]=q[i-1]; q[0]=0; for(i=1;i<=mw;++i)p[i]+=p[i-1]; for(i=mw;i>0;--i)p[i]=p[i-1]; p[0]=0; for(i=0;i<e;++i)h[p[g[i].w]++]=g[i]; for(i=0;i<e;++i)g[q[h[i].t]++]=h[i]; } int main() { init(t); while(t--) { init(n),init(m),--n; for(i=e=mw=0;i<=n;++i)head[i]=-1; while(m--) { init(i),init(j),init(k); if(i!=j)addedge(i,j,k); } for(sum=i=0;i<=n;++i)vis[i]=0; dfs(0); if(sum<n+1) { printf("Case #%d: Possums!\n",++cas); continue; } mysort(); for(i=0;i<=n;++i)fp[i]=p[i]=-1,in[i]=vis[i]=0,mark[i]=i; for(i=0;i<e;++i) if(p[g[i].t]<0)p[g[i].t]=i; huan=1,ans=sum=0; while(huan) { huan=0; for(i=1;i<=n;++i) if(fp[j=mark[i]]>=0) { if(fp[i]<0)in[i]+=w[j],mark[i]=mark[mark[i]]; else { in[i]+=w[i],ans+=w[i]; if(g[++p[fp[i]]].t!=fp[i])p[fp[i]]=-1; } } for(i=0;i<=n;++i)fp[i]=-1,vis[i]=0; for(i=1;i<=n;++i) if(p[i]>=0) { if(fp[j=mark[i]]<0||(fp[j]>=0&&w[j]>g[p[i]].w-in[i])) w[j]=g[p[i]].w-in[i],fp[j]=i,from[j]=mark[g[p[i]].s]; } for(sum=0,i=1;i<=n;++i) if(fp[i]>=0)sum+=w[i]; for(i=1;i<=n;++i) if(!vis[i]) { r=0,j=i; while(j>0&&vis[j]>=0) { if(vis[j]>0) { huan=1; while(q[--r]!=j)mark[q[r]]=j,vis[q[r]]=-1; vis[j]=-1; } else if(!vis[j])vis[q[r++]=j]=1; if(fp[j]>=0)j=from[j]; else j=-1; } while(r--)vis[q[r]]=fp[q[r]]=-1; } } printf("Case #%d: %d\n",++cas,ans+sum); } return 0; }
普通版本1
#include<cstdio> #include<cmath> #define type int using namespace std; const int mm=44444; const int mn=1111; const int oo=1000000000; type c[mm],in[mn],ans; int s[mm],t[mm],id[mn],pre[mn],q[mn]; type Directed_MST(int root,int NV,int NE) { type ret=0; int i,j,u,v,cnt,r; while(1) { for(i=0;i<=NV;++i)in[i]=oo; for(i=0;i<NE;++i) if((u=s[i])!=(v=t[i])&&in[v]>c[i]) pre[v]=u,in[v]=c[i]; pre[root]=-1,in[root]=0; for(i=1;i<=NV;++i) if(in[i]==oo)return -1; for(i=1;i<=NV;++i)id[i]=-1,ret+=in[i]; for(cnt=0,i=1;i<=NV;++i) if(id[i]<0) { r=0,j=i; while(j>=0&&id[j]<0) { if(id[j]==-2) { id[j]=++cnt; while(q[--r]!=j)id[q[r]]=cnt; } else id[q[r++]=j]=-2,j=pre[j]; } while(r--)id[q[r]]=++cnt; } if(cnt==NV)break; for(i=0;i<NE;++i) { j=t[i],s[i]=id[s[i]],t[i]=id[t[i]]; if(s[i]!=t[i])c[i]-=in[j]; } NV=cnt; root=id[root]; } return ret; } int main() { int n,m,e,T,cas=0; scanf("%d",&T); while(T--) { scanf("%d%d",&n,&m),--n; e=0; while(m--)scanf("%d%d%d",&s[e],&t[e],&c[e]),e+=(s[e]!=t[e]); ans=Directed_MST(0,n,e); if(ans<0)printf("Case #%d: Possums!\n",++cas); else printf("Case #%d: %d\n",++cas,ans); } return 0; }
普通版本2
#include<cstdio> #include<cmath> #define type int using namespace std; const int mm=44444; const int mn=1111; type c[mm],in[mn],w[mn],ans; int s[mm],t[mm],id[mn],pre[mn],q[mn],vis[mn]; type Directed_MST(int root,int NV,int NE) { type ret=0,sum=0,tmp; int i,j,u,v,r; bool huan=1; for(i=0;i<=NV;++i)in[i]=0,id[i]=i,pre[i]=-1; while(huan) { for(i=0;i<=NV;++i) if(pre[j=id[i]]>=0) { if(pre[i]<0)in[i]+=w[j],id[i]=id[j]; else in[i]+=w[i],ret+=w[i]; } for(i=0;i<=NV;++i)pre[i]=-1,vis[i]=0; for(i=0;i<NE;++i) if((u=id[s[i]])!=(v=id[t[i]])&&(w[v]>(tmp=c[i]-in[t[i]])||pre[v]<0)) pre[v]=u,w[v]=tmp; for(i=1;i<=NV;++i) if(i!=root&&id[i]==i&&pre[i]<0)return -1; for(pre[root]=-1,sum=i=0;i<=NV;++i) if(pre[i]>=0)sum+=w[i]; for(i=huan=0;i<=NV;++i) if(!vis[i]) { r=0,j=i; while(j>=0&&vis[j]>=0) { if(vis[j]>0) { while(q[--r]!=j)id[q[r]]=j,vis[q[r]]=-1; huan=1,vis[j]=-1; } else vis[q[r++]=j]=1,j=pre[j]; } while(r--)vis[q[r]]=pre[q[r]]=-1; } } return ret+sum; } int main() { int n,m,e,T,cas=0; scanf("%d",&T); while(T--) { scanf("%d%d",&n,&m),--n; e=0; while(m--)scanf("%d%d%d",&s[e],&t[e],&c[e]),e+=(s[e]!=t[e]); ans=Directed_MST(0,n,e); if(ans<0)printf("Case #%d: Possums!\n",++cas); else printf("Case #%d: %d\n",++cas,ans); } return 0; }