Alternate Numbers

Easy

0/40

Average time to solve is 30m

Contributed by

62 upvotes

Problem statement

There is an array ‘A’ of size ‘N’ with an equal number of positive and negative elements.

Without altering the relative order of positive and negative numbers, you must return an array of alternative positive and negative values.

Note:

Start the array with a positive number.

For example

Input:
A = [1, 2, -4, -5], N = 4
Output:
1 -4  2 -5
Explanation: 
Positive elements = 1, 2
Negative elements = -4, -5
To maintain relative ordering, 1 must occur before 2, and -4 must occur before -5.

Detailed explanation ( Input/output format, Notes, Images )

Input Format:

The first line contains an integer, ‘N’.
The second line has ‘N’ integers denoting the array ‘A’.

Output Format:-

You must return an array with alternate positive and negative values.

Note:-

You don’t need to print anything. Just implement the given function.

Constraints:

2 <= N <= 10^5 
-10^9 <= A[i] <= 10^9, A[i] != 0
N%2==0

Time Limit: 1 sec

Sample Input 1:

6 
1 2 -3 -1 -2 3

Sample Output 1:

1 -3 2 -1 3 -2

Explanation Of Sample Input 1:

Testcase 1:
Input:
A = [1, 2, -3, -1, -2, 3], N = 6
Output:
1 -3 2 -1 3 -2
Explanation: 
Positive elements = 1, 2, 3
Negative elements = -3, -1, -2
To maintain relative ordering, 1 should come before 2, and 2 must come before 3.
Also, -3 should come before -1, and -1 must come before -2.

Sample Input 2:

4
-2 -3 4 5

Sample Output 2:

4 -2 5 -3

Console