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Rearrange positive and negative numbers.cpp

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+#include <iostream> 
+using namespace std; 
+
+class GFG 
+{ 
+    public: 
+    void rearrange(int [],int); 
+    void swap(int *,int *); 
+    void printArray(int [],int); 
+}; 
+
+// The main function that rearranges  
+// elements of given array. It puts 
+// positive elements at even indexes  
+// (0, 2, ..) and negative numbers  
+// at odd indexes (1, 3, ..). 
+void GFG :: rearrange(int arr[], int n) 
+{ 
+    // The following few lines are  
+    // similar to partition process 
+    // of QuickSort. The idea is to  
+    // consider 0 as pivot and 
+    // divide the array around it. 
+    int i = -1; 
+    for (int j = 0; j < n; j++) 
+    { 
+        if (arr[j] < 0) 
+        { 
+            i++; 
+            swap(&arr[i], &arr[j]); 
+        } 
+    } 
+
+    // Now all positive numbers are at  
+    // end and negative numbers at the 
+    // beginning of array. Initialize  
+    // indexes for starting point of 
+    // positive and negative numbers  
+    // to be swapped 
+    int pos = i + 1, neg = 0; 
+
+    // Increment the negative index by  
+    // 2 and positive index by 1, 
+    // i.e., swap every alternate negative  
+    // number with next positive number 
+    while (pos < n && neg < pos &&  
+                     arr[neg] < 0) 
+    { 
+        swap(&arr[neg], &arr[pos]); 
+        pos++; 
+        neg += 2; 
+    } 
+} 
+
+// A utility function  
+// to swap two elements 
+void GFG :: swap(int *a, int *b) 
+{ 
+    int temp = *a; 
+    *a = *b; 
+    *b = temp; 
+} 
+
+// A utility function to print an array 
+void GFG :: printArray(int arr[], int n) 
+{ 
+    for (int i = 0; i < n; i++) 
+        cout << arr[i] << " "; 
+} 
+
+// Driver Code 
+int main()  
+{ 
+    int arr[] = {-1, 2, -3, 4,  
+                  5, 6, -7, 8, 9}; 
+    int n = sizeof(arr) / sizeof(arr[0]); 
+    GFG test; 
+    test.rearrange(arr, n); 
+    test.printArray(arr, n); 
+    return 0; 
+}