[kuangbin带你飞]专题六 最小生成树 POJ 2421 Constructing Roads

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<cmath>
 5 #include<cstring>
 6 #include<string>
 7 #define cl(a,b) memset(a,b,sizeof(a))
 8 #define debug(x) cerr<<#x<<"=="<<(x)<<endl
 9 using namespace std;
10 typedef long long ll;
11 
12 const int maxn=110;
13 
14 int f[maxn],tol,n,m;
15 
16 struct _edge
17 {
18     int u,v,w;
19 }edge[maxn*maxn*maxn];
20 
21 bool cmp(_edge a,_edge b)
22 {
23     return a.w<b.w;
24 }
25 
26 void addedge(int u,int v,int w)
27 {
28     edge[tol].u=u;
29     edge[tol].v=v;
30     edge[tol].w=w;
31     tol++;
32 }
33 
34 int _find(int x)
35 {
36     if(f[x]==-1) return x;
37     else return f[x]=_find(f[x]);
38 }
39 
40 int kruskal()
41 {
42     cl(f,-1);
43     sort(edge,edge+tol,cmp);
44     int cnt=0,ans=0;
45     int u,v,w,f1,f2;
46     for(int i=0; i<tol; i++)
47     {
48         u=edge[i].u;
49         v=edge[i].v;
50         w=edge[i].w;
51         f1=_find(u);
52         f2=_find(v);
53         if(f1!=f2)
54         {
55             ans+=w;
56             f[f1]=f2;
57             cnt++;
58         }
59         if(cnt==n-1) break;
60     }
61     return ans;
62 }
63 
64 int main()
65 {
66     while(scanf("%d",&n)!=EOF&&n)
67     {
68         tol=0;
69         for(int i=0;i<n;i++)
70         {
71             for(int j=0;j<n;j++)
72             {
73                 int x;
74                 scanf("%d",&x);
75                 addedge(i,j,x);
76             }
77         }
78         scanf("%d",&m);
79         for(int i=0;i<m;i++)
80         {
81             int x,y;
82             scanf("%d%d",&x,&y);
83             addedge(x-1,y-1,0);
84             addedge(y-1,x-1,0);
85         }
86         printf("%d\n",kruskal()); 
87     }
88     return 0;
89 }
90 /*
91 
92 3
93 0 990 692
94 990 0 179
95 692 179 0
96 1
97 1 2
98 
99 */