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How many pointers are required to reverse a link list?
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Answer / prits
Using 3 pointers:
curr, next, result pointers, curr points to current node,
next obviously points to the next node, result points to
the new reversed linked list
void reverse_single_linked_list(struct node** headRef)
{
struct node* result = NULL;
struct node* current = *headRef;
struct node* next;
while (current != NULL)
{
next = current->next; // tricky: note the next node
current->next = result; // move the node onto the result
result = current;
current = next;
}
*headRef = result;
}
| Is This Answer Correct ? | 14 Yes | 1 No |
Answer / patrick
You cannot must have a pointer to a pointer if you want to
modify the pointer.
void reverse(node** head)
{
node* cur = *head;
*head = null;
while (cur)
{
node* next = cur->next;
cur->next = *head;
*head = cur;
cur = next;
}
}
Besides the head pointer, you will need two local pointers.
| Is This Answer Correct ? | 4 Yes | 1 No |
Answer / vivek
using 2 pointer:
void reverse(node* head_in_out)
{
if(head_in_out)
{
node* aCurr = head_in_out;
node* aNext = NULL;
while (aCurr)
{
head_in_out = aCurr->next;
aCurr->next = aNext;
aNext = aCurr;
aCurr = head_in_out;
}
}
}
| Is This Answer Correct ? | 1 Yes | 2 No |
Answer / vivek
# 3 using 2 pointer:
void reverse(node* head_in_out)
{
if(head_in_out)
{
node* aCurr = head_in_out;
node* aNext = NULL;
while (aCurr)
{
head_in_out = aCurr->next;
aCurr->next = aNext;
aNext = aCurr;
aCurr = head_in_out;
}
head_in_out = aNext; // Bug in above 3rd answer.
}
}
| Is This Answer Correct ? | 1 Yes | 2 No |
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