Minimum cost spanning tree

/* Program for constructing a minimum cost spanning tree  */

#define infinity 9999
#define MAX 20
#include<stdio.h>
#include<stdlib.h>
int G[MAX][MAX],spanning[MAX][MAX],n;

/**** Functions and structures used for Kruskal's Algorithm */
typedef struct edge
{ int u,v,w;
}edge;

typedef struct edgelist
 { edge data[30];
   int n;
 }edgelist;
edgelist elist,spanlist;
int find(int belongs[],int vertexno);
void sort();
void union1(int belongs[],int c1,int c2); //merging of two components
void print();
void kruskal();

int main()
{
int i,j,op;
do {
   printf("\n\n1)Create\n2)Kruskal\n3)Quit");
   printf("\nEnter Your Choice : ");
   scanf("%d",&op);
   switch(op)
    { case 1:
     printf("\nEnter No. of vertices : ");
     scanf("%d",&n);
     printf("\nEnter the adjacency matrix :");
     for(i=0;i<n;i++)
for(j=0;j<n;j++)
 scanf("%d",&G[i][j]);
      break;
case 2: kruskal();break;

     }
}while(op!=3);
}
void kruskal()
{  int belongs[MAX],i,j,cno1,cno2;
   /*create a list of edges */
   elist.n=0;
   for(i=0;i<n;i++)
     for(j=0;j<n;j++)
       if(G[i][j]!=0)
{ elist.data[elist.n].u=i;
  elist.data[elist.n].v=j;
  elist.data[elist.n].w=G[i][j];
  elist.n++;
}
   sort();
 // create the spanning tree with n components
 for(i=0;i<n;i++)
    belongs[i]=i;
 spanlist.n=0;
 // add edges one by one to spanning tree
 for(i=0;i<elist.n;i++)
  { cno1=find(belongs,elist.data[i].u);
    cno2=find(belongs,elist.data[i].v);
    if(cno1 != cno2) // if the edge does not cause a cycle
      { spanlist.data[spanlist.n++]=elist.data[i];
union1(belongs,cno1,cno2);
      }
   }
 //print the spanning tree
  print();
}

int find(int belongs[] ,int vertexno)
 { return(belongs[vertexno]);
 }

void union1(int belongs[], int c1 , int c2)
 { int i;
   for(i=0;i<n;i++)
    if(belongs[i]==c2) // merge two components
      belongs[i]=c1;
 }
void sort()
 { int i,j;
   edge temp;
   for(i=1;i<elist.n;i++)
     for(j=0;j<elist.n-i;j++)
       if(elist.data[j].w > elist.data[j+1].w)
 { temp=elist.data[j];
   elist.data[j]=elist.data[j+1];
   elist.data[j+1]=temp;
 }
  }

void print()
 { int i,cost=0;
   for(i=0;i<spanlist.n;i++)
     { printf("\n%d - %d cost= %d",spanlist.data[i].u,spanlist.data[i].v,
  spanlist.data[i].w);
       cost=cost+spanlist.data[i].w;
     }
   printf("\nCost of the spanning tree : %d",cost);
}