Rotate Array
Rotating an array to the right by k
steps can be achieved in a few ways. One simple method is to reverse parts of the array to get the final rotated array. Here’s a step-by-step guide:
- Handle Multiple Rotations: If
k
is greater than the length of the array, you only need to rotatek % len(nums)
steps. - Reverse the Entire Array: First, reverse the entire array.
- Reverse the First k Elements: Then, reverse the first
k
elements. - Reverse the Remaining Elements: Finally, reverse the remaining
len(nums) - k
elements.
These steps will rotate the array to the right by k
steps without using extra space.
Here’s the code:
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Explanation:
- By performing these reversals, you effectively rotate the array to the right by
k
steps. - The
reverse
function is used to reverse the elements in the range[start, end]
. - This solution modifies the array in place without using extra space, and it meets the problem’s constraints.
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Problem Classification
Language Agnostic Coding Drills
Basic Syntax and Structure: Understand how to declare a function, define parameters, and write function bodies.
Basic Data Types: Understand what are integers, lists, and strings, and how to use them.
Variables and Assignment: Learn how to assign values to variables, and how to update their values.
List Indexing: Learn how to access individual elements in a list using indices.
Slicing: Understand how to slice lists to access a subset of the elements.
List Methods: Understand built-in list methods like
len()
to find the length of a list.Arithmetic Operations: Understand basic arithmetic operations like modulus (
%
).Class Structure: Learn how to create a class and define methods within a class.
Slice Assignment: Understand how to assign a new list to a slice of an existing list.
List Reversing: Understand how to reverse a list or a slice of a list using
[::-1]
.
These concepts, when understood and practiced separately, can be combined to understand and implement the provided code.
Targeted Drills in Python
Basic Syntax and Structure:
1 2 3
# Define a function called greet that prints "Hello, World!". def greet(): pass # Your code here
Basic Data Types:
1
# Declare an integer variable named "my_int" with value 10, a list variable named "my_list" with values 1, 2, 3 and a string variable named "my_str" with value "Hello".
Variables and Assignment:
1
# Declare a variable "a" with value 5, then assign the value 10 to "a".
List Indexing:
1 2
# Given the list "numbers" below, print the second element of the list. numbers = [5, 8, 2, 4, 7, 10]
Slicing:
1 2
# Given the list "numbers", print the sublist containing the second to fourth elements (inclusive). numbers = [5, 8, 2, 4, 7, 10]
List Methods:
1 2
# Given the list "numbers", print the length of the list. numbers = [5, 8, 2, 4, 7, 10]
Arithmetic Operations:
1
# Calculate the modulus of 10 and 3, and print the result.
Class Structure:
1
# Define a class called "MyClass" with a method called "my_method" that prints "This is my method.".
Slice Assignment:
1 2
# Given the list "numbers" below, replace the second and third elements with 20 and 30, respectively. numbers = [5, 8, 2, 4, 7, 10]
List Reversing:
1 2
# Given the list "numbers" below, create a new list that is the reverse of "numbers". numbers = [5, 8, 2, 4, 7, 10]