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Python: Create a list whose ith element is the maximum of the first i elements of the input list

Python Programming Puzzles: Exercise-24 with Solution

Write a Python program to create a list whose ith element is the maximum of the first i elements from a input list.

Input:
[0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]
Output:
[0, 0, 3, 8, 8, 9, 9, 14, 14, 14, 14, 14, 14, 17, 41, 41, 41, 41, 41, 41]

Input:
[6, 5, 4, 3, 2, 1]
Output:
[6, 6, 6, 6, 6, 6]

Input:
[1, 19, 5, 15, 5, 25, 5]
Output:
[1, 19, 19, 19, 19, 25, 25]

Pictorial Presentation:

Python: Create a list whose ith element is the maximum of the first i elements of the input list.

Sample Solution-1:

Python Code:

#License: https://bit.ly/3oLErEI

def test(nums):
    return [max(nums[:i]) for i in range(1, len(nums) + 1)]
nums = [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]
print("Original list:")
print(nums)
print("List whose ith element is the maximum of the first i elements of the said list:")
print(test(nums))
nums = [6,5,4,3,2,1]
print("\nOriginal list:")
print(nums)
print("List whose ith element is the maximum of the first i elements of the said list:")
print(test(nums))
nums = [1,19,5,15,5,25,5]
print("\nOriginal list:")
print(nums)
print("List whose ith element is the maximum of the first i elements of the said list:")
print(test(nums))

Sample Output:

Original list:
[0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]
List whose ith element is the maximum of the first i elements of the said list:
[0, 0, 3, 8, 8, 9, 9, 14, 14, 14, 14, 14, 14, 17, 41, 41, 41, 41, 41, 41]

Original list:
[6, 5, 4, 3, 2, 1]
List whose ith element is the maximum of the first i elements of the said list:
[6, 6, 6, 6, 6, 6]

Original list:
[1, 19, 5, 15, 5, 25, 5]
List whose ith element is the maximum of the first i elements of the said list:
[1, 19, 19, 19, 19, 25, 25]

Flowchart:

Flowchart: Python - Create a list whose ith element is the maximum of the first i elements of the input list.

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Sample Solution-2:

Python Code:

#License: https://bit.ly/3oLErEI

def test(nums):
    return [max(nums[:i+1]) for i in range(len(nums))]

nums = [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]
print("Original list:")
print(nums)
print("List whose ith element is the maximum of the first i elements of the said list:")
print(test(nums))
nums = [6,5,4,3,2,1]
print("\nOriginal list:")
print(nums)
print("List whose ith element is the maximum of the first i elements of the said list:")
print(test(nums))
nums = [1,19,5,15,5,25,5]
print("\nOriginal list:")
print(nums)
print("List whose ith element is the maximum of the first i elements of the said list:")
print(test(nums))

Sample Output:

Original list:
[0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]
List whose ith element is the maximum of the first i elements of the said list:
[0, 0, 3, 8, 8, 9, 9, 14, 14, 14, 14, 14, 14, 17, 41, 41, 41, 41, 41, 41]

Original list:
[6, 5, 4, 3, 2, 1]
List whose ith element is the maximum of the first i elements of the said list:
[6, 6, 6, 6, 6, 6]

Original list:
[1, 19, 5, 15, 5, 25, 5]
List whose ith element is the maximum of the first i elements of the said list:
[1, 19, 19, 19, 19, 25, 25]

Flowchart:

Flowchart: Python - Create a list whose ith element is the maximum of the first i elements of the input list.

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Python Code Editor :

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m