Merge pull request #172 from Abhi-sheKkK/rearrange_by_sign

added a question 'rearrange by sign pairs'

python/rearrange_by_sign.py

@@ -0,0 +1,30 @@
+'''
+Question : We have been given an array containing even number of elements , also same number of positive
+           and negative elements are present , we have to make pairs of positive and negative elements in the array
+           such that , the order of array should not be lost.
+Example: Input= arr=[3,1,-2,-5,2,-4]
+         Output=[3,-2,1,-5,2,-4]
+Explanation:The positive integers in nums are [3,1,2]. The negative integers are [-2,-5,-4].
+            The only possible way to rearrange them such that they satisfy all conditions is [3,-2,1,-5,2,-4].
+            Other ways such as [1,-2,2,-5,3,-4], [3,1,2,-2,-5,-4], [-2,3,-5,1,-4,2] are incorrect because they 
+            do not satisfy one or more conditions.    
+
+Approach : we will separate the positive and negative numbers in different arrays so that the order is preserved
+           then add them to a single array alternatively in the order .
+
+'''
+
+
+class Solution:
+    def rearrangeArray(self, nums: list[int]) -> list[int]:
+        # Separate positive and negative numbers
+        positives = [num for num in nums if num > 0]
+        negatives = [num for num in nums if num < 0]
+
+        # Merge them by alternating between positive and negative numbers
+        result = []
+        for i in range(len(positives)):
+            result.append(positives[i])
+            result.append(negatives[i])
+
+        return result