Minimum Cost of a Spanning Tree in C Programming

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#include <stdio.h>
#include <conio.h>
#include <alloc.h>
 
struct lledge
{
    int v1, v2 ;
    float cost ;
    struct lledge *next ;
} ;
 
int stree[5] ;
int count[5] ;
int mincost ;
 
struct lledge * kminstree ( struct lledge *, int ) ;
int getrval ( int ) ;
void combine ( int, int ) ;
void del ( struct lledge * ) ;
 
void main( )
{
    struct lledge *temp, *root ;
    int i ;
 
    clrscr( ) ;
 
    root = ( struct lledge * ) malloc ( sizeof ( struct lledge ) ) ;
 
    root -> v1 = 4 ;
    root -> v2 = 3 ;
    root -> cost = 1 ;
    temp = root -> next = ( struct lledge * ) malloc ( sizeof ( struct lledge ) ) ;
 
    temp -> v1 = 4 ;
    temp -> v2 = 2 ;
    temp -> cost = 2 ;
    temp -> next =(struct lledge*)malloc(sizeof(struct lledge)) ;
 
    temp = temp -> next ;
    temp -> v1 = 3 ;
    temp -> v2 = 2 ;
    temp -> cost = 3 ;
    temp -> next =(struct lledge*)malloc(sizeof(struct lledge));
 
    temp = temp -> next ;
    temp -> v1 = 4 ;
    temp -> v2 = 1 ;
    temp -> cost = 4 ;
    temp -> next = NULL ;
 
    root = kminstree ( root, 5 ) ;
 
    for ( i = 1 ; i <= 4 ; i++ )
        printf ( "\nstree[%d] -> %d", i, stree[i] ) ;
    printf ( "\nThe minimum cost of spanning tree is %d", mincost ) ;
    del ( root ) ;
 
    getch( ) ;
}
struct lledge * kminstree ( struct lledge *root, int n )
{
    struct lledge *temp = NULL ;
    struct lledge *p, *q ;
    int noofedges = 0 ;
    int i, p1, p2 ;
 
    for ( i = 0 ; i < n ; i++ )
        stree[i] = i ;
    for ( i = 0 ; i < n ; i++ )
        count[i] = 0 ;
 
    while ( ( noofedges < ( n - 1 ) ) && ( root != NULL ) )
    {
        p = root ;
 
        root = root -> next ;
 
        p1 = getrval ( p -> v1 ) ;
        p2 = getrval ( p -> v2 ) ;
 
        if ( p1 != p2 )
        {
            combine ( p -> v1, p -> v2 ) ;
            noofedges++ ;
            mincost += p -> cost ;
            if ( temp == NULL )
            {
                temp = p ;
                q = temp ;
            }
            else
            {
                q -> next = p ;
                q = q -> next ;
            }
            q -> next = NULL ;
        }
    }
    return temp ;
}
 
int getrval ( int i )
{
    int j, k, temp ;
    k = i ;
    while ( stree[k] != k )
        k = stree[k] ;
    j = i ;
    while ( j != k )
    {
        temp = stree[j] ;
        stree[j] = k ;
        j = temp ;
    }
    return k ;
}
 
void combine ( int i, int j )
{
    if ( count[i] < count[j] )
        stree[i] = j ;
    else
    {
        stree[j] = i ;
        if ( count[i] == count[j] )
            count[j]++ ;
    }
}
 
void del ( struct lledge *root )
{
    struct lledge *temp ;
 
    while ( root != NULL )
    {
        temp = root -> next ;
        free ( root ) ;
        root = temp ;
    }
}

Posted in: Programming in C , Tree