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

Last update on April 17 2025 13:03:06 (UTC/GMT +8 hours)

Max of First i Elements

Write a Python program to create a list whose i^th element is the maximum of the first i elements from an 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]

Visual Presentation:

Sample Solution-1:

Python Code:

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

# Define a function named 'test' that takes a list of numbers 'nums' as input
def test(nums):
    # List comprehension to create a list of maximum values for each prefix of the input list
    # Iterate through the indices from 1 to the length of 'nums' + 1
    # For each index 'i', find the maximum value in the prefix nums[:i]
    return [max(nums[:i]) for i in range(1, len(nums) + 1)]

# Assign a specific list of numbers 'nums' to the variable
nums = [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]

# Print the original list of numbers 'nums'
print("Original list:")
print(nums)

# Print a message indicating the operation to be performed
print("List whose ith element is the maximum of the first i elements of the said list:")

# Print the result of the test function applied to the 'nums' list
print(test(nums))

# Assign a different list of numbers 'nums' to the variable
nums = [6, 5, 4, 3, 2, 1]

# Print the original list of numbers 'nums'
print("\nOriginal list:")
print(nums)

# Print a message indicating the operation to be performed
print("List whose ith element is the maximum of the first i elements of the said list:")

# Print the result of the test function applied to the updated 'nums' list
print(test(nums))

# Assign another list of numbers 'nums' to the variable
nums = [1, 19, 5, 15, 5, 25, 5]

# Print the original list of numbers 'nums'
print("\nOriginal list:")
print(nums)

# Print a message indicating the operation to be performed
print("List whose ith element is the maximum of the first i elements of the said list:")

# Print the result of the test function applied to the updated 'nums' 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:

Sample Solution-2:

Python Code:

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

# Define a function named 'test' that takes a list of numbers 'nums' as input
def test(nums):
    # List comprehension to create a list of maximum values for each prefix of the input list
    # Iterate through the indices from 0 to the length of 'nums'
    # For each index 'i', find the maximum value in the prefix nums[:i+1]
    return [max(nums[:i+1]) for i in range(len(nums))]

# Assign a specific list of numbers 'nums' to the variable
nums = [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]

# Print the original list of numbers 'nums'
print("Original list:")
print(nums)

# Print a message indicating the operation to be performed
print("List whose ith element is the maximum of the first i elements of the said list:")

# Print the result of the test function applied to the 'nums' list
print(test(nums))

# Assign a different list of numbers 'nums' to the variable
nums = [6, 5, 4, 3, 2, 1]

# Print the original list of numbers 'nums'
print("\nOriginal list:")
print(nums)

# Print a message indicating the operation to be performed
print("List whose ith element is the maximum of the first i elements of the said list:")

# Print the result of the test function applied to the updated 'nums' list
print(test(nums))

# Assign another list of numbers 'nums' to the variable
nums = [1, 19, 5, 15, 5, 25, 5]

# Print the original list of numbers 'nums'
print("\nOriginal list:")
print(nums)

# Print a message indicating the operation to be performed
print("List whose ith element is the maximum of the first i elements of the said list:")

# Print the result of the test function applied to the updated 'nums' 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:

For more Practice: Solve these Related Problems:

• Write a Python program to create a list where the ith element is the maximum of the first i elements of an input list.
• Write a Python program using a loop to compute the running maximum for a given list of integers.
• Write a Python program to implement this functionality with the accumulate function from itertools.
• Write a Python program to generate a list of running maximums by iterating and comparing current elements to a stored maximum.

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