acm 2395

 1#include<stdio.h>
 2#include<stdlib.h>
 3#define INFINITY 1000000001
 4
 5long N,M;
 6long r[2000][2000];
 7struct item
 8{
 9    int v;
10    int lowcost;
11}closeedge[2000];
12
13int Prim(int v)
14{
15    int i,j,w,v0;
16    long min,d[2000];
17    min = INFINITY;
18    for(i=0;i<N;i++)
19    {
20        if(i != v)
21        {
22            closeedge[i].v = v;
23            closeedge[i].lowcost = r[v][i];
24        }
25                   d[i] = 0;
26    }
27    closeedge[v].lowcost = 0;
28    for(i = 1;i < N;i++)
29    {
30        min = INFINITY;
31        for(w = 0;w < N; w++)
32        {
33            if(closeedge[w].lowcost>0 && closeedge[w].lowcost<min)
34            {
35                min = closeedge[w].lowcost;
36                v0 = w;
37            }
38        }
39        d[v0] = closeedge[v0].lowcost;
40        closeedge[v0].lowcost = 0;
41        for(j = 0;j<N;j++)
42        {
43            if(r[v0][j] < closeedge[j].lowcost)
44            {
45                closeedge[j].lowcost = r[v0][j];
46                closeedge[j].v = v0;
47            }
48        }
49        
50    }
51    min = 0;
52    for(j=0;j<N;j++)
53    {
54        if(d[j]>min)
55            min = d[j];
56    }
57    return min;
58}
59void initialize()
60{
61    int i,j;
62    for(i=0;i<N;i++)
63        for(j=0;j<N;j++)
64            r[i][j] = INFINITY;
65}
66main()
67{
68    
69    int i,x,y;
70    long temp;
71    scanf("%ld%ld",&N,&M);
72    //memset(r,INFINITY,sizeof(r));
73    initialize();
74    for(i = 0;i<M;i++)
75    {
76    
77        scanf("%d%d%ld",&x,&y,&temp);
78                  if(r[x-1][y-1]<INFINITY)
79                  {
80            if(r[x-1][y-1]>temp)
81                       {
82                           r[x-1][y-1] = r[y-1][x-1] = temp;
83
84                        }
85                  }
86                  else
87                  {
88                        r[x-1][y-1] = r[y-1][x-1] = temp;
89
90                  }
91    }
92
93    printf("%ld\n",Prim(0));
94}
95