Added Merge Sort , Bubble sort and Heap Operations with Python

Data Structures/Heap/Python/heap.py

@@ -0,0 +1,62 @@
+# Import the heap functions from python library
+from heapq import heappush, heappop, heapify
+
+# heappop - pop and return the smallest element from heap
+# heappush - push the value item onto the heap, maintaining
+#             heap invarient
+# heapify - transform list into heap, in place, in linear time
+
+# A class for Min Heap
+class MinHeap:
+
+    # Constructor to initialize a heap
+    def __init__(self):
+        self.heap = []
+
+    def parent(self, i):
+        return int((i-1)/2)
+
+    # Inserts a new key 'k'
+    def insertKey(self, k):
+        heappush(self.heap, k)
+
+    # Decrease value of key at index 'i' to new_val
+    # It is assumed that new_val is smaller than heap[i]
+    def decreaseKey(self, i, new_val):
+        self.heap[i]  = new_val
+        while(i != 0 and self.heap[self.parent(i)] > self.heap[i]):
+            # Swap heap[i] with heap[parent(i)]
+            self.heap[i] , self.heap[self.parent(i)] = (
+            self.heap[self.parent(i)], self.heap[i])
+
+    # Method to remove minium element from min heap
+    def extractMin(self):
+        return heappop(self.heap)
+
+    # This functon deletes key at index i. It first reduces
+    # value to minus infinite and then calls extractMin()
+    def deleteKey(self, i):
+        self.decreaseKey(i, float("-inf"))
+        self.extractMin()
+
+    # Get the minimum element from the heap
+    def getMin(self):
+        return self.heap[0]
+
+# Driver pgoratm to test above function
+heapObj = MinHeap()
+heapObj.insertKey(3)
+heapObj.insertKey(2)
+heapObj.deleteKey(1)
+heapObj.insertKey(15)
+heapObj.insertKey(5)
+heapObj.insertKey(4)
+heapObj.insertKey(45)
+
+print(heapObj.extractMin()),
+print(heapObj.getMin()),
+heapObj.decreaseKey(2, 1)
+print(heapObj.getMin())
+
+
+#heap implementation by Prakhar Varshney

Sorting/Bubble Sort/Python/bubble.py

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+def bubble_sort(arr):
+    size = len(arr)
+    for i in range(size):
+        for j in range(0,size-i-1):
+            if arr[j]>arr[j+1]:
+                arr[j],arr[j+1] = arr[j+1],arr[j]
+
+
+test_arr = [ 12, 11, 13, 5, 6, 7]
+print("List before sorting")
+print(test_arr)
+bubble_sort(test_arr)
+print("List After Sorting")
+print(test_arr)
+
+#Bubble Sorting by Prakhar Varshney

Sorting/Merge Sort/Python/merge_sort.py

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+def merge(arr,left,mid,right):
+    n1 = (mid-left)  + 1
+    n2 = right-mid
+
+    Left_arr = [0]*(n1)
+    Right_arr = [0]*(n2)
+
+    for i in range(0,n1):
+        Left_arr[i] = arr[left + i]
+
+    for j in range(0, n2):
+        Right_arr[j] = arr[mid + 1 +j]
+
+    i = 0
+    j = 0
+    k = left
+
+    while(i < n1 and j < n2):
+        if(Left_arr[i]<=Right_arr[j]):
+            arr[k] = Left_arr[i]
+            i = i+1
+        else:
+            arr[k] = Right_arr[j]
+            j = j+1
+        k = k+1
+
+    while(i<n1):
+        arr[k] = Left_arr[i]
+        i = i+1
+        k = k+1
+
+    while(j<n2):
+        arr[k] = Right_arr[j]
+        j = j+1
+        k = k+1
+
+def mergeSort(arr,left,right):
+    if(left<right):
+        mid = int((left+(right-1))/2)
+
+        mergeSort(arr,left,mid)
+        mergeSort(arr,mid+1,right)
+        merge(arr,left,mid,right)
+
+
+arr = []
+size = int(input("Enter the size"))
+
+for i in range(0,size):
+    a = int(input())
+    arr.append(a)
+
+n = len(arr)
+print("List before sorting")
+print(arr)
+
+mergeSort(arr,0,n-1)
+print("sorted list ")
+print(arr)