added file selection sort, heap sort, merge sort, insertion sort

Code/heap_sort.py

@@ -0,0 +1,46 @@
+def heapify(arr, n, i):
+    largest = i  # Initialize largest as root
+    l = 2 * i + 1     # left = 2*i + 1
+    r = 2 * i + 2     # right = 2*i + 2
+
+    # See if left child of root exists and is
+    # greater than root
+    if l < n and arr[i] < arr[l]:
+        largest = l
+
+    # See if right child of root exists and is
+    # greater than root
+    if r < n and arr[largest] < arr[r]:
+        largest = r
+
+    # Change root, if needed
+    if largest != i:
+        arr[i], arr[largest] = arr[largest], arr[i]  # swap
+
+        # Heapify the root.
+        heapify(arr, n, largest)
+
+# The main function to sort an array of given size
+
+
+def heapSort(arr):
+    n = len(arr)
+
+    # Build a maxheap.
+    # Since last parent will be at ((n//2)-1) we can start at that location.
+    for i in range(n // 2 - 1, -1, -1):
+        heapify(arr, n, i)
+
+    # One by one extract elements
+    for i in range(n-1, 0, -1):
+        arr[i], arr[0] = arr[0], arr[i]   # swap
+        heapify(arr, i, 0)
+
+
+# Driver code to test above
+arr = [12, 11, 13, 5, 6, 7]
+heapSort(arr)
+n = len(arr)
+print("Sorted array is")
+for i in range(n):
+    print("%d" % arr[i]),

Code/insertion_sort.py

@@ -0,0 +1,23 @@
+def insertionSort(arr):
+
+    # Traverse through 1 to len(arr)
+    for i in range(1, len(arr)):
+
+        key = arr[i]
+
+        # Move elements of arr[0..i-1], that are
+        # greater than key, to one position ahead
+        # of their current position
+        j = i-1
+        while j >= 0 and key < arr[j]:
+            arr[j+1] = arr[j]
+            j -= 1
+        arr[j+1] = key
+
+
+# Driver code to test above
+arr = [12, 11, 13, 5, 6]
+insertionSort(arr)
+print("Sorted array is:")
+for i in range(len(arr)):
+    print("%d" % arr[i])

Code/merge_sort.py

@@ -0,0 +1,71 @@
+def merge(arr, l, m, r):
+    n1 = m - l + 1
+    n2 = r - m
+
+    # create temp arrays
+    L = [0] * (n1)
+    R = [0] * (n2)
+
+    # Copy data to temp arrays L[] and R[]
+    for i in range(0, n1):
+        L[i] = arr[l + i]
+
+    for j in range(0, n2):
+        R[j] = arr[m + 1 + j]
+
+    # Merge the temp arrays back into arr[l..r]
+    i = 0     # Initial index of first subarray
+    j = 0     # Initial index of second subarray
+    k = l     # Initial index of merged subarray
+
+    while i < n1 and j < n2:
+        if L[i] <= R[j]:
+            arr[k] = L[i]
+            i += 1
+        else:
+            arr[k] = R[j]
+            j += 1
+        k += 1
+
+    # Copy the remaining elements of L[], if there
+    # are any
+    while i < n1:
+        arr[k] = L[i]
+        i += 1
+        k += 1
+
+    # Copy the remaining elements of R[], if there
+    # are any
+    while j < n2:
+        arr[k] = R[j]
+        j += 1
+        k += 1
+
+# l is for left index and r is right index of the
+# sub-array of arr to be sorted
+
+
+def mergeSort(arr, l, r):
+    if l < r:
+
+        # Same as (l+r)//2, but avoids overflow for
+        # large l and h
+        m = (l+(r-1))//2
+
+        # Sort first and second halves
+        mergeSort(arr, l, m)
+        mergeSort(arr, m+1, r)
+        merge(arr, l, m, r)
+
+
+# Driver code to test above
+arr = [12, 11, 13, 5, 6, 7]
+n = len(arr)
+print("Given array is")
+for i in range(n):
+    print("%d" % arr[i]),
+
+mergeSort(arr, 0, n-1)
+print("\n\nSorted array is")
+for i in range(n):
+    print("%d" % arr[i]),

Code/selection_sort.py

@@ -0,0 +1,21 @@
+import sys
+A = [64, 25, 12, 22, 11]
+
+# Traverse through all array elements
+for i in range(len(A)):
+
+    # Find the minimum element in remaining
+    # unsorted array
+    min_idx = i
+    for j in range(i+1, len(A)):
+        if A[min_idx] > A[j]:
+            min_idx = j
+
+    # Swap the found minimum element with
+    # the first element
+    A[i], A[min_idx] = A[min_idx], A[i]
+
+# Driver code to test above
+print("Sorted array")
+for i in range(len(A)):
+    print("%d" % A[i])