USACO:Agri-Net解题报告

思路：最小生成树，prim算法解.

 

 

/*
ID: xpli1
PROG: agrinet
LANG: C
*/

#include
#include
#include

#define max(a,b) (((a) > (b)) ? (a) : (b))
#define min(a,b) (((a) < (b)) ? (a) : (b))

#define INT_MAX 0x7fffffff
#define IN stdin
#define OUT stdout

int weight[101][101];
int distance[101];
int source[101];
int intree[101];
int N,treesize,treecost;

void prim()
{
 int i,j,k;
 for(i=0; i   distance[i] = INT_MAX;
  source[i] = -1;
  intree[i] = 0;
 }

 treesize  = 1;
 treecost  = 0;
 intree[0] = 1;
 for(i=1; i   distance[i] = weight[0][i];
  source[i] =  0;
 }

 while(treesize < N){
  int MIN = INT_MAX;
  for(j=0; j    if(!intree[j] && MIN > distance[j]){
    k = j;
    MIN = distance[k];
   }
  }

  treesize++;
  treecost += distance[k];
  intree[k] = 1;

  for(j=0; j    if(!intree[j] && distance[j] > weight[k][j]){
    distance[j] = weight[k][j];
    source[j] = k;
   }
  }
 }

 return;
}

int main(void)
{
 FILE* fin = fopen("agrinet.in","r");
 FILE* fout = fopen("agrinet.out","w");

 fscanf(IN,"%d",&N);

 int i=0;

 while(i

 prim();

 fprintf(OUT,"%d/n",treecost);

 return 0;
}