SDE - 1

class Node:

# Constructor to initialize the node object
def __init__(self, data):
self.data = data
self.next = None


class LinkedList:

# Function to initialize head
def __init__(self):
self.head = None

# Function to pairwise swap elements of a linked list
def pairwiseSwap(self):
temp = self.head

# There are no nodes in linked list
if temp is None:
return

# Traverse further only if there are at least two
# left
while(temp and temp.next):

# If both nodes are same,
# no need to swap data
if(temp.data != temp.next.data):

# Swap data of node with its next node's data
temp.data, temp.next.data = temp.next.data, temp.data

# Move temp by 2 to the next pair
temp = temp.next.next

# Function to insert a new node at the beginning
def push(self, new_data):
new_node = Node(new_data)
new_node.next = self.head
self.head = new_node

# Utility function to print the LinkedList
def printList(self):
temp = self.head
while(temp):
print temp.data,
temp = temp.next


# Driver program
llist = LinkedList()
llist.push(5)
llist.push(4)
llist.push(3)
llist.push(2)
llist.push(1)

print "Linked list before calling pairWiseSwap() "
llist.printList()
llist.pairwiseSwap()

print "\nLinked list after calling pairWiseSwap()"
llist.printList

# Recursive Python program to find key
# closest to k in given Binary Search Tree.

# Utility that allocates a new node with the
# given key and NULL left and right pointers.
class newnode:

# Constructor to create a new node
def __init__(self, data):
self.key = data
self.left = None
self.right = None

# Function to find node with minimum
# absolute difference with given K
# min_diff --> minimum difference till now
# min_diff_key --> node having minimum absolute
# difference with K
def maxDiffUtil(ptr, k, min_diff, min_diff_key):
if ptr == None:
return

# If k itself is present
if ptr.key == k:
min_diff_key[0] = k
return

# update min_diff and min_diff_key by
# checking current node value
if min_diff > abs(ptr.key - k):
min_diff = abs(ptr.key - k)
min_diff_key[0] = ptr.key

# if k is less than ptr->key then move
# in left subtree else in right subtree
if k < ptr.key:
maxDiffUtil(ptr.left, k, min_diff,
min_diff_key)
else:
maxDiffUtil(ptr.right, k, min_diff,
min_diff_key)

# Wrapper over maxDiffUtil()
def maxDiff(root, k):

# Initialize minimum difference
min_diff, min_diff_key = 999999999999, [-1]

# Find value of min_diff_key (Closest
# key in tree with k)
maxDiffUtil(root, k, min_diff, min_diff_key)

return min_diff_key[0]

# Driver Code
if __name__ == '__main__':
root = newnode(9)
root.left = newnode(4)
root.right = newnode(17)
root.left.left = newnode(3)
root.left.right = newnode(6)
root.left.right.left = newnode(5)
root.left.right.right = newnode(7)
root.right.right = newnode(22)
root.right.right.left = newnode(20)
k = 18
print(maxDiff(root, k))

The kernel is basically a computer program usually considered the central component or module of an OS. It is responsible for handling, managing, and controlling all operations of computer systems and hardware. Whenever the system starts, the kernel is loaded first and remains in the main memory. It also acts as an interface between user applications and hardware.