Reverse of linked list

(1) reverse of the linked list

The original linked list retains a head node, which can be used to traverse the content of each node in the table, use two pointers to direct the content pointer in the linked list to the next node, and change it to the previous node. This will reverse the linked list!

# Include <stdio. h>

# Include <stdlib. h>

Struct llist

{

Int num;

Struct llist * next;

};

Typedef struct llist node;

Typedef node * llink;

 

Void printllist (llink ptr)

{

While (ptr! = NULL)

{

Printf ("[% d]", ptr-> num );

Ptr = ptr-> next;

}

Printf ("\ n ");

}

Llink createllist (int * array, int len)

{

Llink head;

Llink ptr, ptr1;

Int I;

Head = (llink) malloc (sizeof (node ));

If (! Head)

Return NULL;

Head-> num = array [0];

Head-> next = NULL;

Ptr = head;

For (I = 1; I <len; I ++)

{

Ptr1 = (llink) malloc (sizeof (node ));

If (! Ptr1)

Return NULL;

Ptr1-> num = array [I];

Ptr-> next = NULL;

Ptr-> next = ptr1;

Ptr = ptr-> next;

}

Return head;

}

// Implementation process of chain table Inversion

Llink invertllist (llink head)

{

Llink mid, last;

Mid = NULL;

While (head! = NULL)

{

Last = mid;

Mid = head;

Head = head-> next;

Mid-> next = last;

}

Return mid;

}

 

Void freellist (llink head)

{

Llink ptr;

While (head! = NULL)

{

Ptr = head;

Head = head-> next;

Free (ptr );

}

}

Int main ()

{

Int llist [6] = {1, 2, 3, 4, 5, 6 };

Llink head;

 

Head = createllist (llist, 6 );

If (! Head)

{

Exit (1 );

}

Printllist (head );

Head = invertllist (head );

Printllist (head );

Printllist (head );

Return 0;

}

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