reverse linked list

Question:
Reverse a singly linked list.

Approach

A property of a linked list is that you can prepend to the head in O(1). With this we can just prepend to the head each node as we traverse the linked list.

We have to remember to create a temp variable to hold the current value so we don’t break the original linked list when setting the value’s next to be the new linked list’s old head.

Solution

var reverseList = function(head) {
    if(head === null || head.next === null) {
        return head;
    }
    var curr = head;
    var temp = head;
    var newHead = null;
    while(curr !== null) {
        temp = curr;
        curr = temp.next;
        temp.next = newHead;
        newHead = temp;
    }
    return newHead;
};