Python for Coding Interviews part 2

In Python, there are several loop constructs commonly used for solving array problems. Here are the most common ones:

1. For Loop: The for loop is widely used for iterating over elements in an array or any iterable object.

   It allows you to execute a block of code for each element in the array. 

   arr = [1, 2, 3, 4, 5]
   for num in array: 
     print(num)

    

2. While Loop:

   The while loop is used when you need to execute a block of code repeatedly as long as a condition is true.

   It's often used when you don't know in advance how many iterations are needed.
   

   i = 0 
   while i < len(array): 
     print(array[i]) 
     i += 1

    

3. Nested Loops: Nested loops involve placing one loop inside another loop. They are used when you need to iterate over elements of a multi-dimensional array or perform operations that require multiple levels of iteration. For example:

   
   

   matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] for row in matrix: for num in row: print(num)

4. List Comprehensions: List comprehensions provide a concise way to create lists based on existing lists. They are often used to apply transformations or filters to arrays. For example:

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   squares = [x ** 2 for x in arr]

5. Enumerate: The enumerate() function is used to iterate over both the elements and their indices in an array. It returns tuples containing the index and the corresponding element. For example:

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   for i, num in enumerate(arr): print(f"Element at index {i} is {num}")

These loop constructs provide the foundation for iterating over arrays and performing various operations on them in Python. Understanding how to use them effectively is crucial for solving array problems efficiently.