Added Sorting algorithms in C++

Author: saiharsha-22

data_structures/C++/QUICKSOR.CPP

@@ -0,0 +1,55 @@
+//quick sort program time complexity in average case O(nlogn)
+
+#include<iostream>
+using namespace std;
+void quicksort (int[], int, int);
+int main ()
+{
+  int a[50], n, i;
+  cout<<"enter number of elemnts that u want to store:\n";
+  cin>>n;
+  for (i = 0; i < n; i++)
+    {
+      cin>>a[i];
+    }
+  quicksort (a, 0, n - 1);
+  for (i = 0; i < n; i++)
+    {
+      cout<<"\t"<<a[i];
+    }
+ return 0;
+}
+
+void
+quicksort (int a[], int low, int high)
+{
+  int pivot, i, j, temp;
+  if (low < high)
+    {
+      pivot = low;
+      i = low;
+      j = high;
+      while (i < j)
+	{
+	  while (a[i] <= a[pivot] && i <= high)
+	    {
+	      i++;
+	    }
+	  while (a[j] > a[pivot] && j >= low)
+	    {
+	      j--;
+	    }
+	  if (i < j)
+	    {
+	      temp = a[i];
+	      a[i] = a[j];
+	      a[j] = temp;
+	    }
+	}
+      temp = a[j];
+      a[j] = a[pivot];
+      a[pivot] = temp;
+      quicksort (a, low, j - 1);
+      quicksort (a, j + 1, high);
+    }
+}

data_structures/C++/SELECTIO.CPP

@@ -0,0 +1,35 @@
+//Selection sort algorithm works with an time complexity of O(n^2)
+#include<iostream>
+using namespace std;
+int main ()
+{
+  int a[50], n, i, j, min, temp;
+  cout<<"enter number of elements that u want to store:\n";
+  cin>>n;
+  for (i = 0; i < n; i++)
+    {
+      cin>>a[i];
+    }
+  for (i = 0; i < n - 1; i++)
+    {
+      min = i;
+      for (j = i + 1; j < n; j++)
+	{
+	  if (a[min] > a[j])
+	    {
+	      min = j;
+	    }
+	}
+      if (min != i)
+	{
+	  temp = a[i];
+	  a[i] = a[min];
+	  a[min] = temp;
+	}
+    }
+  for (i = 0; i < n; i++)
+    {
+      cout<<"\t"<<a[i];
+    }
+  return 0;
+}

data_structures/C++/SHELLSOR.CPP

@@ -0,0 +1,69 @@
+
+// Shell sort algorithm time complexity is best case O(nlogn) and worst case O(n^2)
+
+#include<iostream>
+using namespace std;
+class shellsort
+{
+private:
+  int a[20], n, i, j, gap, temp;
+public:
+  void getdata ()
+  {
+    cout << "enter number of elemnts:\n";
+    cin >> n;
+    cout << "enter the elements:\n";
+    for (i = 0; i < n; i++)
+      {
+	cin >> a[i];
+      }
+  }
+  void shellsorting ()
+  {
+
+    for (gap = n / 2; gap > 0; gap = gap / 2)
+      {
+	for (j = gap; j < n; j++)
+	  {
+	    for (i = j - gap; i >= 0; i -= gap)
+	      {
+		if (a[i + gap] > a[i])
+		  {
+		    break;
+		  }
+		else
+		  {
+		    swap ();
+		  }
+	      }
+	  }
+      }
+  }
+  void swap ()
+  {
+    temp = a[i + gap];
+    a[i + gap] = a[i];
+    a[i] = temp;
+
+  }
+  void display ()
+  {
+    for (i = 0; i < n; i++)
+      {
+	cout << a[i] << "\t";
+      }
+  }
+};
+
+int main ()
+{
+
+  shellsort obj;
+  obj.getdata ();
+  cout << "before sorting:";
+  obj.display ();
+  obj.shellsorting ();
+  cout << endl << "after sorting:";
+  obj.display ();
+  return 0;
+}