Program to Check if Array can be Sorted with One Swap

Python Program to Check if Array can be Sorted with One Swap

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In the previous article, we have discussed Python Program for Maximum Distance between Two Occurrences of Same Element in Array/List
Given a list and the task is to check to see if the given list can be sorted with a single swap.

copy() method:

The list’s shallow copy is returned by the copy() method.

There are no parameters to the copy() method.

It creates a new list. It makes no changes to the original list.

Examples:

Example1:

Input:

Given List = [7, 8, 9]

Output:

The given list [7, 8, 9] can be sorted with a single swap

Explanation:

When we swap 7 and 9 we get [9, 8, 7] which is a sorted list.

Example2:

Input:

Given List = [6, 3, 2, 1]

Output:

The given list [6, 3, 2, 1] cannot be sorted with a single swap

Program to Check if Array can be Sorted with One Swap in Python:

Below are the ways to check to see if the given list can be sorted with a single swap.

Method #1: Using For Loop (Static Input)

Approach:

  • Give the list as static input and store it in a variable.
  • Copy the given list in a variable say “new_lst” using the copy() function.
  • Take a variable say ‘c’ and initialize its value with 0.
  • Sort the above obtained “new_lst”.
  • Loop until the length of the “new_lst” using the for loop.
  • Check if the given list element is not equal to the new_lst element using the if conditional statement.
  • If the statement is true then increment the count value of ‘c’ by 1 and store it in the same variable ‘c‘.
  • Check if the value of ‘c’ is equal to 0 or true using the if conditional statement and ‘or ‘ keyword.
  • If the statement is true, print “The given list can be sorted with a single swap”.
  • If it is false, then print “The given list cannot be sorted with a single swap”.
  • The Exit of the Program.

Below is the implementation:

# Give the list as static input and store it in a variable.
gven_lst = [7, 8, 9]
# Copy the given list in a variable say "new_lst" using the copy() function.
new_lst = gven_lst.copy()
# Take a variable say 'c' and initialize its value with 0.
c = 0
# Sort the above obtained "new_lst".
new_lst.sort()
# Loop until the length of the "new_lst" using the for loop.
for i in range(len(new_lst)):
 # Check if the given list element is not equal to the new_lst element using the
    # if conditional statement.
    if(gven_lst[i] != new_lst[i]):
     # If the statement is true then increment the count value of 'c' by 1 and
        # store it in the same variable 'c'.
        c += 1
# Check if the value of 'c' is equal to 0 or true using the if conditional statement
# and 'or ' keyword.
if(c == 0 or c == 2):
  # If the statement is true, print "The given list can be sorted with a single swap".
    print("The given list", gven_lst, "can be sorted with a single swap")
 # If it is false, then print "The given list cannot be sorted with a single swap".
else:
    print("The given list", gven_lst, "cannot be sorted with a single swap")

Output:

The given list [7, 8, 9] can be sorted with a single swap

Method #2: Using For loop (User Input)

Approach:

  • Give the list as user input using list(),map(),input(),and split() functions.
  • Store it in a variable.
  • Copy the given list in a variable say “new_lst” using the copy() function.
  • Take a variable say ‘c’ and initialize its value with 0.
  • Sort the above obtained “new_lst”.
  • Loop until the length of the “new_lst” using the for loop.
  • Check if the given list element is not equal to the new_lst element using the if conditional statement.
  • If the statement is true then increment the count value of ‘c’ by 1 and store it in the same variable ‘c‘.
  • Check if the value of ‘c’ is equal to 0 or true using the if conditional statement and ‘or ‘ keyword.
  • If the statement is true, print “The given list can be sorted with a single swap”.
  • If it is false, then print “The given list cannot be sorted with a single swap”.
  • The Exit of the Program.

Below is the implementation:

# Give the list as user input using list(),map(),input(),and split() functions.
#Store it in a variable.
gven_lst = list(map(int, input(
   'Enter some random List Elements separated by spaces = ').split()))
# Copy the given list in a variable say "new_lst" using the copy() function.
new_lst = gven_lst.copy()
# Take a variable say 'c' and initialize its value with 0.
c = 0
# Sort the above obtained "new_lst".
new_lst.sort()
# Loop until the length of the "new_lst" using the for loop.
for i in range(len(new_lst)):
 # Check if the given list element is not equal to the new_lst element using the
    # if conditional statement.
    if(gven_lst[i] != new_lst[i]):
     # If the statement is true then increment the count value of 'c' by 1 and
        # store it in the same variable 'c'.
        c += 1
# Check if the value of 'c' is equal to 0 or true using the if conditional statement
# and 'or ' keyword.
if(c == 0 or c == 2):
  # If the statement is true, print "The given list can be sorted with a single swap".
    print("The given list", gven_lst, "can be sorted with a single swap")
 # If it is false, then print "The given list cannot be sorted with a single swap".
else:
    print("The given list", gven_lst, "cannot be sorted with a single swap")

Output:

Enter some random List Elements separated by spaces = 5 6 7 12 15
The given list [5, 6, 7, 12, 15] can be sorted with a single swap

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