added sorting algorithms

Author: arncv

Algorithms/Sorting Algorithms/bubblesort.cpp

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+// Question:Bubble Sort Algorithm
+#include <iostream>
+using namespace std;
+
+int n;
+
+void bubble_Sort(int a[])
+{
+
+ 	for(int i=0; i<n-1; i++)
+ 	{
+ 		int flag = 0;  // Declaring a variable to check if elements have been sorted in this iteration.
+ 		for(int j=0; j<n-1-i; j++)
+ 		{
+ 			if(a[j] > a[j+1])
+ 			{
+   			swap(a[j+1], a[j]);
+   			flag = 1;		// Set flag = 1 to signify that the element is sorted.c
+ 			}
+ 		}	
+ 		if (flag == 0)
+ 		{
+ 			// No elements have been swapped, which means that the array is sorted. End the algorithm.
+ 			break;
+ 		}
+ 	}
+}
+
+int main()
+{
+	cout<<"Enter the size of the array"<<endl;
+	cin >> n;
+	int a[n];
+	cout<<"Enter the elements of the array"<<endl;
+	for(int i=0; i<n; i++)
+	cin >> a[i];
+	bubble_Sort(a);
+	cout<<"The sorted array is : "<<endl;
+	for (int i = 0; i < n; i++) {
+		cout << a[i] << '\n';
+  }
+  return 0;
+}

Algorithms/Sorting Algorithms/heapsort.cpp

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+// Question: Heap Sorting Algorithm
+#include <iostream>
+
+using namespace std;
+
+// To heapify a subtree rooted with node i which is
+// an index in arr[]. n is size of heap
+void heapify(int arr[], int n, int i)
+{
+    int largest = i; // Initialize largest as root
+    int l = 2*i + 1; // left = 2*i + 1
+    int r = 2*i + 2; // right = 2*i + 2
+
+    // If left child is larger than root
+    if (l < n && arr[l] > arr[largest])
+        largest = l;
+
+    // If right child is larger than largest so far
+    if (r < n && arr[r] > arr[largest])
+        largest = r;
+
+    // If largest is not root
+    if (largest != i)
+    {
+        swap(arr[i], arr[largest]);
+
+        // Recursively heapify the affected sub-tree
+        heapify(arr, n, largest);
+    }
+}
+
+// main function to do heap sort
+void heapSort(int arr[], int n)
+{
+    // Build heap (rearrange array)
+    for (int i = n / 2 - 1; i >= 0; i--)
+        heapify(arr, n, i);
+
+    // One by one extract an element from heap
+    for (int i=n-1; i>=0; i--)
+    {
+        // Move current root to end
+        swap(arr[0], arr[i]);
+
+        // call max heapify on the reduced heap
+        heapify(arr, i, 0);
+    }
+}
+
+/* A utility function to print array of size n */
+void printArray(int arr[], int n)
+{
+    for (int i=0; i<n; ++i)
+        cout << arr[i] << " ";
+    cout << "\n";
+}
+
+// Driver program
+int main()
+{
+    int arr[] = {12, 11, 13, 5, 6, 7};
+    int n = sizeof(arr)/sizeof(arr[0]);
+
+    heapSort(arr, n);
+
+    cout << "Sorted array is \n";
+    printArray(arr, n);
+} 

Algorithms/Sorting Algorithms/insertionsort.cpp

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+// Question:Insertion Sort Algorithm
+#include <iostream>
+using namespace std;
+
+int n;
+void insertionSort(int A[])
+{
+	int key;
+  for(int i=0;i<n;i++)
+  {
+    key = A[i];
+    int j = i-1;
+    while(j>=0 and key<A[j])
+    {
+      A[j+1] = A[j];
+      j--;
+    }
+    A[j+1]=key;
+    }
+}
+
+int main()
+{
+  std::cout << "Enter the array length: ";
+  std::cin >> n;
+  int A[n];
+  std::cout << "Enter the array elements :" << '\n';
+  for(int i=0; i<n; i++)
+  cin >> A[i];
+  insertionSort(A);
+  std::cout << "Sorted Array :" << '\n';
+  for(int i=0;i<n;i++)
+  cout << A[i] << endl;
+  return 0;
+}

Algorithms/Sorting Algorithms/quicksort.cpp

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+// Question:Program for quick sort implementation in C++.
+
+#include <iostream>
+#include <vector>
+
+int partition(std::vector<int> &A, int start, int end)
+{
+	int temp;
+	int pivot = A[end];
+	int partitionIndex = start; // set partition index as start initially
+	for(int i=start; i<end; i++)
+	{
+		if(A[i] <= pivot)
+		{
+			std::swap(A[i], A[partitionIndex]);
+			partitionIndex++;
+		}
+	}
+	std::swap(A[partitionIndex], A[end]);		//	partition index
+
+	return partitionIndex;
+}
+
+void swapElements(int* elementOne, int* elementTwo)
+{
+	int temp = *elementOne;
+	*elementOne = *elementTwo;
+	*elementTwo = temp;
+}
+std::vector<int> quick_sort(std::vector<int> &A, int start, int end)
+{
+/*        std::cout<<"Current list : \n";
+        for(int i=0;i<A.size();i++)
+        {
+                std::cout<<A[i]<<" ";
+        }
+        std::cout<<"\nSorted list : \n";
+*/
+	
+	if(start<end)
+	{
+		int partitionIndex = partition(A,start,end);
+		quick_sort(A,start,partitionIndex-1);
+		quick_sort(A,partitionIndex+1, end);
+	}
+
+/*        for(int i=0;i<A.size();i++)
+        {
+                std::cout<<A[i]<<" ";
+        }
+*/        return A;
+}
+
+int main()
+{
+        std::cout<<"\nTest\n";
+        std::vector<int> arr={10,2,23,-4,235,56,2,6,5,5,5,23,-4,346,-56,81,43,654,435,-54};
+        quick_sort(arr, 0, arr.size()-1);
+        std::cout<<"\n\n\n";
+        for(int i=0;i<arr.size();i++)
+        {
+                std::cout<<arr[i]<<" ";
+        }
+        return 0;
+}

Algorithms/Sorting Algorithms/selectionsort.cpp

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+// Question:Selection Sot Algorithm
+#include<iostream>
+using namespace std;
+void swapping(int &a, int &b) { 
+   int temp;
+   temp = a;
+   a = b;
+   b = temp;
+}
+void display(int *array, int size) {
+   for(int i = 0; i<size; i++)
+      cout << array[i] << " ";
+   cout << endl;
+}
+void selectionSort(int *array, int size) {
+   int i, j, imin;
+   for(i = 0; i<size-1; i++) {
+      imin = i;
+      for(j = i+1; j<size; j++)
+         if(array[j] < array[imin])
+            imin = j;
+         swap(array[i], array[imin]);
+   }
+}
+int main() {
+   int n;
+   cout << "Enter the number of elements: ";
+   cin >> n;
+   int arr[n];
+   cout << "Enter elements:" << endl;
+   for(int i = 0; i<n; i++) {
+      cin >> arr[i];
+   }
+   cout << "Array before Sorting: ";
+   display(arr, n);
+   selectionSort(arr, n);
+   cout << "Array after Sorting: ";
+   display(arr, n);
+}