bzoj 1196: [HNOI2006]公路修建问题

2016-06-23

难得一见的水题 我竟然wa了好几次，并不想多说什么。

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<queue>
 7 #define ll long long
 8 #define M 1000009
 9 using namespace std;
10 ll read()
11 {
12     char ch=getchar();
13     ll x=0,f=1;
14     for(;ch<'0'||ch>'9';ch=getchar())
15       if(ch=='-')
16         f=-1;
17     for(;ch>='0'&&ch<='9';ch=getchar())
18       x=x*10+ch-'0';
19     return x*f;
20 }
21 int n,k,m,fa[M],ans=0x7fffffff;
22 struct data
23 {
24     int u,v,v1;
25 }a[M],b[M];
26 bool cmp(data a1,data a2)
27 {
28     return a1.v1<a2.v1;
29 }
30 int zhao(int x)
31 {
32     if(fa[x]==x)
33       return x;
34     return fa[x]=zhao(fa[x]);
35 }
36 void pan(int x)
37 {
38     int sum=0,mx=0;
39     for(int i=1;i<=n;i++)
40       fa[i]=i;
41     for(int i=1;i<=m;i++)
42       {
43           int a1=zhao(a[i].u),a2=zhao(a[i].v);
44           if(a1!=a2)
45             {
46                 fa[a1]=a2;
47                 sum++;
48                 mx=a[i].v1;
49               if(sum==x)
50                 break;
51           }
52       }
53     for(int i=1;i<=m;i++)
54       {
55           int a1=zhao(a[i].u),a2=zhao(a[i].v);
56           if(a1!=a2)
57             {
58                 fa[a1]=a2;
59                 sum++;
60                 mx=max(b[i].v1,mx);
61           }
62       }
63     ans=mx;
64 }
65 int main()
66 {
67     n=read();
68     k=read();
69     m=read();
70     for(int i=1;i<=m;i++)
71       {
72           a[i].u=read();
73           a[i].v=read();
74           b[i]=a[i];
75           a[i].v1=read();
76           b[i].v1=read();
77       }
78     sort(a+1,a+m+1,cmp);
79     sort(b+1,b+m+1,cmp);
80     pan(k);
81     printf("%d\n",ans);
82     return 0;
83 }

 

posted @ 2016-06-23 08:07  xiw5  阅读(129)  评论(0)  编辑  收藏  举报