HDU 4738 Caocao's Bridges 桥(2013 ACM/ICPC Asia Regional Chengdu Online 1002)

彩笔请多指教！

转载请注明出处__谢谢！ http://www.cnblogs.com/HaibaraAi/articles/3340115.html by---HaibaraAi 求认识大神（ˇ＾ˇ），目前只会水题- -#~~~！

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=4738

 1 #include <cstdio>
 2 #include <vector>
 3 #include <cstring>
 4 #include <algorithm>
 5 using namespace std;
 6 #define maxn 1001
 7 #define INF 0x7fffffff
 8 struct Edge{
 9     int from,to,w;
10 };
11 vector<Edge>edges;
12 vector<int>G[maxn];
13 int pre[maxn];
14 int vis[maxn];
15 int ans[maxn];
16 int n,m,k,mmin,dfs_clock;
17 void init(){
18     for(int i=0;i<n;i++)G[i].clear();
19     edges.clear();
20 }
21 void Ade(int from,int to,int w){
22     edges.push_back((Edge){from,to,w});
23     edges.push_back((Edge){to,from,w});
24     int m=edges.size();
25     G[from].push_back(m-2);
26     G[to].push_back(m-1);
27 }
28 int dfs(int u,int p){
29     vis[u]=1;
30     int cnt=0;
31     int lowu=pre[u]=++dfs_clock;
32     for(int i=0;i<G[u].size();i++){
33         Edge e=edges[G[u][i]];
34         if(!pre[e.to]){
35             int lowv=dfs(e.to,u);
36             lowu=min(lowu,lowv);
37             if(lowv>pre[u]){
38                 if(e.w==0)ans[k++]=1;
39                 else ans[k++]=e.w;
40             }
41         }
42         else if(e.to!=p||cnt>=1){if(pre[e.to]<pre[u])lowu=min(lowu,pre[e.to]);}
43         else cnt++;
44     }
45     return lowu;
46 }
47 int main(){
48     while(~scanf("%d%d",&n,&m)&&(n+m)){
49         init();
50         memset(ans,0,sizeof ans);
51         memset(pre,0,sizeof pre);
52         memset(vis,0,sizeof vis);
53         for(int i=0;i<m;i++){
54             int a,b,w;
55             scanf("%d%d%d",&a,&b,&w);
56             a--;b--;
57             Ade(a,b,w);
58         }
59         mmin=INF;
60         k=dfs_clock=0;
61         dfs(0,-1);
62         for(int i=0;i<k;i++)if(mmin>ans[i])mmin=ans[i];
63         for(int i=0;i<n;i++)if(!vis[i]){k=1;mmin=0;break;}
64         if(k==0)printf("-1\n");
65         else printf("%d\n",mmin);
66     }
67     return 0;
68 }

View Code 2013-09-26 08:56:21

posted @ 2013-09-26 08:59 HaibaraAi 阅读(156) 评论(0) 收藏举报

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