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Error

Given a **L**inked **l**ist, rearrange it such that converted list should be of the form a < b > c < d > e < f .. where **a, b, c** are consecutive data node of linked list and such that the order of linked list is sustained.

**For example:** In 11 15 20 5 10 we consider only 11 20 5 15 10 because it satisfies the above condition and the order of linked list. 5 20 11 15 10 is not considered as it does not follow the order of linked list.

To maintain the order, keep swapping the **adjacent** nodes of the linked list (whenever required) to get the desired output.

**Example 1:**

**Input:
**LinkedList: 1->2->3->4
**Output: **1 3 2 4

**Example 2:**

**Input:
**LinkedList: 11->15->20->5->10
**Output: **11 20 5 15 10**
Explanation: **In the given linked list,
after arranging them as 11 < 20 > 5
< 15 > 10 in the pattern as asked above.

**Your Task:**

The task is to complete the function **zigZag**() which should reorder the list as required and return the head of the linked list.

**Expected Time Complexity:** O(N)

**Expected Auxiliary Space:** O(1)

**Constraints:**

1 <= size of linked list(a) <= 1000

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Linked List in Zig-Zag fashion

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