alternate_partionFun_quickSort.cpp

int partitionArray(int input[], int start, int end) {
  int pivot = input[start];
  // Count elements smaller than pivot and swap
  int count = 0; 
  for(int i = start+1; i <= end; i++) {
    if(input[i] <= pivot) {
        count++;
    }
   }
   int pivotIndex = start + count; 
   int temp = input[start];
   input[start] = input[pivotIndex]; 
   input[pivotIndex] = temp; 
   // ensure left half contains elements smaller than pivot 
   // and right half larger 
   int i = start, j = end; 
   while(i <= pivotIndex && j >= pivotIndex) { 
      while(input[i] <= pivot) {
        i++; 
      }
      while(input[j] > pivot) { 
        j--;
      }
      if(i < pivotIndex && j > pivotIndex) {
        int temp = input[i]; 
        input[i] = input[j];
        input[j] = temp;
        i++;
        j--;
      }
    }
    
    return pivotIndex;
   }