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Language/Type: C++ linked lists pointers
Author: Marty Stepp (on 2016/12/05)

Write a function named consume that accepts two references to pointers to the front of linked lists. After the call is done, all the elements from the second list should be appended to the end of the first one in the same order, and the second list should be empty (null). Note that either linked list could be initially empty. For example, if we start with the following lists, we will get the results shown below:

list1: {1, 3, 5, 7}
list2: {2, 4, 6}
after consume(list1, list2);
list1: {1, 3, 5, 7, 2, 4, 6}
list2: {}
after consume(list2, list1);
list1: {}
list2: {2, 4, 6, 1, 3, 5, 7}

Constraints: 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)
Type your C++ solution code here:

This is a function problem. Write a C++ function as described. Do not write a complete program; just the function(s) above.

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