Hi friends and guiders I have another problem which is a C program to insert and delete nodes and edges in an undirected graph using adjacency matrix.

I have goggled this i got some programs which had many errors. But i got following one which is better than them but still does not run. please help me by rectifying and correcting it.

#include<stdio.h>
#define max 20
int adj[ max ][ max ];
int n;
main()
{
int choice;
int node, origin, destin;
create_graph();
while ( 1 )
{
printf( "1.Insert a node\n" );
printf( "2.Insert an edge\n" );
printf( "3.Delete a node\n" );
printf( "4.Delete an edge\n" );
printf( "5.Dispaly\n" );
printf( "6.Exit\n" );
printf( "Enter your choice : " );
scanf( "%d", &choice );
switch ( choice )
{
case 1:
insert_node();
break;
case 2:
printf( "Enter an edge to be inserted : " );
fflush( stdin );
scanf( "%d %d", &origin, &destin );
insert_edge( origin, destin );
break;
case 3:
printf( "Enter a node to be deleted : " );
fflush( stdin );
scanf( "%d", &node );
delete_node( node );
break;
case 4:
printf( "Enter an edge to be deleted : " );
fflush( stdin );
scanf( "%d %d", &origin, &destin );
del_edge( origin, destin );
break;
case 5:
display();
break;
case 6:
exit();
default:
printf( "Wrong choice\n" );
break;
}
}
}
create_graph()
{
int i, max_edges, origin, destin;
printf( "Enter number of nodes : " );
scanf( "%d", &n );
max_edges = n * ( n – 1 );
for ( i = 1;i <= max_edges;i++ )
{
printf( "Enter edge %d( 0 0 ) to quit : ", i );
scanf( "%d %d", &origin, &destin );
if ( ( origin == 0 ) && ( destin == 0 ) )
break;
if ( origin > n || destin > n || origin <= 0 || destin <= 0 )
{
printf( "Invalid edge!\n" );
i–;
}
else
adj[ origin ][ destin ] = 1;
}
}
display()
{
int i, j;
for ( i = 1;i <= n;i++ )
{
for ( j = 1;j <= n;j++ )
printf( "%4d", adj[ i ][ j ] );
printf( "\n" );
}
}
insert_node()
{
int i;
n++;
printf( "The inserted node is %d \n", n );
for ( i = 1;i <= n;i++ )
{
adj[ i ][ n ] = 0;
adj[ n ][ i ] = 0;
}
}
delete_node( char u )
{
int i, j;
if ( n == 0 )
{
printf( "Graph is empty\n" );
return ;
}
if ( u > n )
{
printf( "This node is not present in the graph\n" );
return ;
}
for ( i = u;i <= n – 1;i++ )
for ( j = 1;j <= n;j++ )
{
adj[ j ][ i ] = adj[ j ][ i + 1 ];
adj[ i ][ j ] = adj[ i + 1 ][ j ];
}
n–;
}
insert_edge( char u, char v )
{
if ( u > n )
{
printf( "Source node does not exist\n" );
return ;
}
if ( v > n )
{
printf( "Destination node does not exist\n" );
return ;
}
adj[ u ][ v ] = 1;
}
del_edge( char u, char v )
{
if ( u > n || v > n || adj[ u ][ v ] == 0 )
{
printf( "This edge does not exist\n" );
return ;
}
adj[ u ][ v ] = 0;
}