Discussion on Reverse a linked list Challenge

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2 weeks ago+ 0 comments

public static SinglyLinkedListNode reverse(SinglyLinkedListNode llist) {

if(llist == null) return null; if(llist.next == null) return llist;

    SinglyLinkedListNode curr = llist;
    SinglyLinkedListNode prev = null;
    SinglyLinkedListNode temp = null; 

    while(curr != null){
        temp = curr.next;
        //point curr node to prev
        curr.next = prev;
        //set prev = curr node
        prev = curr;
        curr = temp;
    }

    return prev;
}

1 month ago+ 0 comments

My Java solution with o(n) time complexity and o(1) space complexity:

public static SinglyLinkedListNode reverse(SinglyLinkedListNode llist) {
        if(llist == null) return null;
        if(llist.next == null) return llist;
        
        SinglyLinkedListNode curr = llist;
        SinglyLinkedListNode prev = null;
        SinglyLinkedListNode temp = null; 
        
        while(curr != null){
            temp = curr.next;
            //point curr node to prev
            curr.next = prev;
            //set prev = curr node
            prev = curr;
            curr = temp;
        }
        
        return prev;
    }

1 month ago+ 0 comments

Here is my c++ solution, you can watch video explanation here : https://youtu.be/F4nGusqPIu0

SinglyLinkedListNode* reverse(SinglyLinkedListNode* llist) {
    SinglyLinkedListNode* reverse = nullptr;
    while(llist != nullptr){
        SinglyLinkedListNode* newNode = new SinglyLinkedListNode(llist->data);
        newNode ->next = reverse;
        reverse = newNode;
        llist = llist->next;
    }
    return reverse;
}

1 month ago+ 0 comments

My short and efficient recursive C++ solution:

SinglyLinkedListNode* reverse(SinglyLinkedListNode* llist) {
    if (llist == nullptr) return nullptr;
    if (llist->next == nullptr) return llist;
    
    SinglyLinkedListNode* newHead = reverse(llist->next);
    llist->next->next = llist;
    llist->next = nullptr;

    return newHead;
}

3 months ago+ 0 comments

public static SinglyLinkedListNode reverse(SinglyLinkedListNode llist) { if (llist == null || llist.next == null) { return llist; }

// Recursively reverse the rest of the list
SinglyLinkedListNode newHead = reverse(llist.next);

// Adjust pointers to reverse the list
llist.next.next = llist; 
llist.next = null;  

return newHead; 
}

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