Write a function named split
that accepts a reference to a pointer to a ListNode
representing the front of a linked list.
Your function should rearrange the elements of the list so that all negative values appear before all of the non-negatives.
The negatives should also appear in the opposite relative order that they appeared in the original list.
For example, suppose a variable named front
points to the front of a list containing the following sequence of values:
{8, 7, -4, 19, 0, 43, -8, -7, 2}
The call of split(front);
should modify the list to contain the following elements, in exactly this order.
Notice that the negatives were in the relative order -7, -8, -4 in the original list and are in the relative order -4, -8, -7 after the call.
{-7, -8, -4, 8, 7, 19, 0, 43, 2}
Constraints:
Do not modify the data
field of existing nodes; change the list by changing pointers only.
Do not construct any new ListNode
objects in solving this problem (though you may create as many ListNode*
pointer variables as you like).
Do not use any auxiliary data structures to solve this problem (no array, vector, stack, queue, string, etc).
Assume that you are using the ListNode
structure as defined below:
struct ListNode {
int data; // value stored in each node
ListNode* next; // pointer to next node in list (nullptr if none)
}