ADJACENCY LIST

Create The Adjacency List Of The Graph Using Link List

Source code :-

#include <stdio.h>
#include <stdlib.h>
typedef struct node
{
    char data;
    struct node *next;
    struct edge *adj;
} node;

typedef struct edge
{
    node *dest;
    struct edge *link;
} edge;

node *start;

node *get1(char x)
{
    node *p;
    p = (node *)malloc(sizeof(node));
    p->data = x;
    p->next = NULL;
    p->adj = NULL;
    return p;
}

edge *get2()
{
    edge *p;
    p = (edge *)malloc(sizeof(edge));
    p->dest = NULL;
    p->link = NULL;
    return p;
}

node *create()
{
    node *p, *q;
    edge *r, *s;
    char x, y;
    while (1)
    {
        fflush(stdin);
        printf("Enter the node (if no vertex then press only [enter]) : ");
        scanf("%c", &x);
        if (x == '\n')
            break;
        p = get1(x);
        if (start == NULL)
            start = p;
        else
            q->next = p;
        q = p;
        printf("\n");
    }
    p = start;
    while (p != NULL)
    {
        printf("\n");
        while (1)
        {
            printf("\nEnter the adjacent vertex of %c (if no vertex then press only [enter]) : ", p->data);        
            fflush(stdin);
            scanf("%c", &x);
            if (x == '\n')
                break;
            q = start;
            while (q != NULL)
            {
                if (x == q->data)
                    break;
                q = q->next;
            }
            if (q == NULL)
                printf("\nPlease enter right value.\n");
            else
            {
                r = get2();
                r->dest = q;
                if (p->adj == NULL)
                    p->adj = r;
                else
                    s->link = r;
                s = r;
            }
        }
        p = p->next;
    }
    return start;
}
void display(node *start)
{
    node *a;
    edge *b;
    if (start == NULL)
    {
        printf("\n\nlink list not exist.\n");
        return;
    }
    a = start;
    printf("\n\nThe required result is:- \n");
    printf("\n| NODE |  | ADJACENCY LIST \n\n");
    while (a != NULL)
    {
        printf("|  %c   |  | ", a->data);
        b = a->adj;
        while (b != NULL)
        {
            printf("%c ", b->dest->data);
            b = b->link;
        }
        a = a->next;
        printf("\n");
    }
}
int main()
{
    create();
    display(start);
    return 1;
}

Input-Output :-

abhi@hp-15q-laptop:~$ gcc adjacency.c
abhi@hp-15q-laptop:~$ ./a.out

Enter the node (if no vertex then press only [enter]) : A

Enter the node (if no vertex then press only [enter]) : B

Enter the node (if no vertex then press only [enter]) : C

Enter the node (if no vertex then press only [enter]) : D

Enter the node (if no vertex then press only [enter]) : E

Enter the node (if no vertex then press only [enter]) : F

Enter the node (if no vertex then press only [enter]) : G

Enter the node (if no vertex then press only [enter]) : H

Enter the node (if no vertex then press only [enter]) : I

Enter the node (if no vertex then press only [enter]) :


Enter the adjacent vertex of A (if no vertex then press only [enter]) : B

Enter the adjacent vertex of A (if no vertex then press only [enter]) : C

Enter the adjacent vertex of A (if no vertex then press only [enter]) : D

Enter the adjacent vertex of A (if no vertex then press only [enter]) :


Enter the adjacent vertex of B (if no vertex then press only [enter]) : A

Enter the adjacent vertex of B (if no vertex then press only [enter]) : E

Enter the adjacent vertex of B (if no vertex then press only [enter]) : F

Enter the adjacent vertex of B (if no vertex then press only [enter]) :


Enter the adjacent vertex of C (if no vertex then press only [enter]) : A

Enter the adjacent vertex of C (if no vertex then press only [enter]) : D

Enter the adjacent vertex of C (if no vertex then press only [enter]) : G    

Enter the adjacent vertex of C (if no vertex then press only [enter]) :


Enter the adjacent vertex of D (if no vertex then press only [enter]) : A

Enter the adjacent vertex of D (if no vertex then press only [enter]) : C

Enter the adjacent vertex of D (if no vertex then press only [enter]) : G

Enter the adjacent vertex of D (if no vertex then press only [enter]) : H

Enter the adjacent vertex of D (if no vertex then press only [enter]) :


Enter the adjacent vertex of E (if no vertex then press only [enter]) : B

Enter the adjacent vertex of E (if no vertex then press only [enter]) : I

Enter the adjacent vertex of E (if no vertex then press only [enter]) :


Enter the adjacent vertex of F (if no vertex then press only [enter]) : B

Enter the adjacent vertex of F (if no vertex then press only [enter]) :


Enter the adjacent vertex of G (if no vertex then press only [enter]) : C

Enter the adjacent vertex of G (if no vertex then press only [enter]) : D

Enter the adjacent vertex of G (if no vertex then press only [enter]) :


Enter the adjacent vertex of H (if no vertex then press only [enter]) : D

Enter the adjacent vertex of H (if no vertex then press only [enter]) :


Enter the adjacent vertex of I (if no vertex then press only [enter]) : E

Enter the adjacent vertex of I (if no vertex then press only [enter]) :


The required result is:-

| NODE |  | ADJACENCY LIST

|  A   |  | B C D
|  B   |  | A E F
|  C   |  | A D G
|  D   |  | A C G H
|  E   |  | B I
|  F   |  | B
|  G   |  | C D
|  H   |  | D
|  I   |  | E