Added Insertion, Bubble, Shell and Merge Sort

Author: shreyasvedpathak

sortingAlgo.py

@@ -16,6 +16,8 @@ def selection(A):
         A[i], A[position] = A[position], A[i]
     print("Sorted using Selection Sort: ", A)
 
+###############################################################
+
 def insertion(A):
     """
     Algo name: Insertion Sort
@@ -37,18 +39,131 @@ def insertion(A):
 
     print("Sorted using Insertion Sort: ", A)
 
+###############################################################
+
+def bubble(A):
+    """
+    Algo name: Bubble Sort
+    STABLE
+    input:
+    A -- Array
+
+    returns sorted array
+    """
+    n = len(A)
+    for p in range(n-1, 0, -1):
+        for i in range(0, p):
+            if A[i] > A[i + 1]:
+                A[i], A[i+1] = A[i+1], A[i]
+    print("Sorted using Bubble Sort: ", A)
+
+###############################################################
+
+def shell(A):
+    """
+    Algo name: Shell Sort
+    UNSTABLE
+    input:
+    A -- Array
+
+    returns sorted array
+    """
+    n = len(A)
+    gap = n//2
+    while gap > 0:
+        i = gap
+        while i < n:
+            temp = A[i]
+            j = i - gap
+            while j >= 0 and A[j] > temp:
+                A[j+gap] = A[j]
+                j = j - gap
+            A[j+gap] = temp
+            i = i + 1
+        gap = gap // 2
+    print("Sorted using Shell Sort: ", A)
+
+###############################################################
+
+def merge(A, l, m, r):
+    """
+    Algo name: Merge
+    input:
+    A -- Array
+    l -- first index position of the array
+    m -- middle index postion of the array calculated
+         using l and r
+    r -- last index position of the array
+
+    returns Sorted partial array A
+    """
+
+    i = l
+    j = m + 1 
+    k = l
+    B = [0] * (r + 1)
+    while i <= m and j <= r:
+        if A[i] < A[j]:
+            B[k] = A[i]
+            i = i + 1
+        else:
+            B[k] = A[j]
+            j = j + 1
+        k = k + 1
+
+    while i <= m:
+        B[k] = A[i]
+        i = i + 1
+        k = k + 1
+    while j <= r:
+        B[k] = A[j]
+        j = j + 1
+        k = k + 1
+    for x in range(l, r + 1):
+        A[x] = B[x]
+
+
+def mergesort(A, left, right):
+    """
+    Algo name: Merge Sort
+    UNSTABLE
+    input:
+    A -- Array
+    left -- first index position of the array(0 in first call)
+    right -- last index position of the array(len(A) - 1 in the first call)
+
+    """
+    if left < right:
+        mid = (left + right) // 2
+        mergesort(A, left, mid)
+        mergesort(A, mid + 1, right)
+        merge(A, left, mid, right) 
+
+
+###############################################################
 def switch_case(choice):
     if choice == 1:
         selection(A),
     elif choice == 2: 
         insertion(A)
+    elif choice == 3: 
+        bubble(A)
+    elif choice == 4: 
+        shell(A)
+    elif choice == 5:
+        mergesort(A, 0, len(A)-1)
+        print("Sorted using Merge Sort: ", A)
 
+###############################################################
 
 A = list(map(int, input("Enter Array elements: ").split()))
 
 print("Select Sorting Method")
 print("1. Selection Sort")
 print("2. Insertion Sort")
+print("3. Bubble Sort")
+print("4. Shell Sort")
+print("5. Merge Sort")
 
 choice = int(input("Enter your choice: "))
 switch_case(choice)