Last Updated: 3 Jun, 2021

# Zig - Zag Array

Easy

## Problem statement

#### For example:

``````Given ‘N’ = 4,
'ARR' = { 4, 3, 2, 1}
Then a possible array is 3, 4, 1, 2.
``````
##### Note:
``````You are supposed to return the array, which is in a zig-zag fashion.

Since there can be multiple answers for a particular array, any of the possible solutions are accepted.

It can be proved. A zig-zag array is always possible for a given array.
``````
##### Input format:
``````The first line of input contains an integer ‘T’ denoting the number of test cases.

The first line of each test case contains a single integer, ‘N,’ where ‘N’ is the number of elements of the array.

The second line of each test case contains ‘N’ space-separated integers, denoting the array elements.
``````
##### Output Format :
``````For each test case, You are supposed to return a zig-zag array for the given array. The runner function will print a single line containing a single integer which denotes whether the returned array is in zig-zag fashion or not.
``````
##### Note:
``````You are not required to print the expected output; it has already been taken care of. Just implement the function.
``````
##### Constraints:
``````1 <= ‘T’ <= 10
1 <= ‘N’ <= 5*10^3
0 <= 'ARR'[i] <= 10 ^ 6

Time Limit: 1sec.
``````

## Approaches

### 01 Approach

The idea is to sort the array and swap the pair of elements starting from index 1 (0-based Indexing).

The steps are as follows:

• Sort the array in ascending order.
• Loop ‘i’ = 0, from index 1 to ‘N’ and at each iteration increase ‘i’ by 2.
• Swap elements at positions ‘i’ and ‘i + 1’.
• We will return the array ‘arr’ as the final answer.