Write the actual code to reverse a linked list

Question

PrinceBoroujerdi · Accepted Answer

//iterative
void Reverse(node** head)
{
    node* prev = null;
    node* current = *head;
    while (current != null)
    {
        node* next = current->next;
        current->next = prev;
        prev = current;
        current = next;
    }
    
    *head = prev;
}

node* head;
node* newHead;
Reverse(head, null, &newHead);

//recursive
void Reverse(node* current, node* prev, node** newHead)
{
    if (current->next != NULL)
    {
        Reverse(current->next, current);
    }
    else
    {
        *newHead = current;
    }
    
    current->next = prev;
}

Redeye · Answer

// Java solution

public static void reverseList (Node start) {
     currentNode = start;
     prevNode = null;
      while (currentNode !=null) {
           // save value of next Node
           nextNode  = currentNode -> next;
   
           // change link
           currentNode -> next = prevNode;
            
            // List traverse
            prevNode = currentNode;
            currentNode = nextNode;;
     }
}

edaSmart · Answer

Node* reverse(Node* head) {
    Node* newHead = NULL;
    Node* node;
    while (head) {
        node = head;
        head = head->next;
        node->next = NULL;
        if (!newHead) {
           newHead = node;
        } else {
           node->next = newHead;
           newHead = node;
        }
    }
    return newHead;
}

Hussein · Answer

void reverse(node* &head) {
    if(head == NULL) return;
    
    node *p = NULL, *cur = head;
    
    while(cur != NULL) {
        node* tmp = cur->nxt;
        cur->nxt = p;
        p = cur;
        cur = tmp;
    }
    
    head = cur;
}

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