Python: List of integers where the sum of the first i integers is i

Last update on April 17 2025 13:03:14 (UTC/GMT +8 hours)

Sum of First i Equals i

Write a Python program to check a given list of integers where the sum of the first i integers is i.

Input:
[0, 1, 2, 3, 4, 5]
Output:
False

Input:
[1, 1, 1, 1, 1, 1]
Output:
True

Input:
[2, 2, 2, 2, 2]
Output:
False

Sample Solution:

Python Code:

# Define a function named 'test' that takes a list 'li' and an integer 'i' as input
def test(li, i):
    # Check if the sum of the first 'i' integers in 'li' equals 'i'
    return sum(li[:i]) == i

# Create a list 'nums' with specific elements
nums = [0, 1, 2, 3, 4, 5]

# Assign an integer 'i' to the variable
i = 1

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

# Print a message indicating the current value of 'i'
print("Check the said list, where the sum of the first i integers is i: i =", i)

# Print the result of the test function applied to the 'nums' list with the current value of 'i'
print(test(nums, 1))

# Update the value of 'i'
i = 3

# Print a message indicating the updated value of 'i'
print("\nOriginal list:")
print(nums)

# Print the result of the test function applied to the 'nums' list with the updated value of 'i'
print("Check the said list, where the sum of the first i integers is i: i =", i)
print(test(nums, 3))

# Update the value of 'i' and 'nums'
i = 6
nums = [1, 1, 1, 1, 1, 1]

# Print a message indicating the updated value of 'i'
print("\nOriginal list:")
print(nums)

# Print the result of the test function applied to the updated 'nums' list with the updated value of 'i'
print("Check the said list, where the sum of the first i integers is i: i =", i)
print(test(nums, 6))

# Update the value of 'i' and 'nums'
i = 2
nums = [2, 2, 2, 2, 2]

# Print a message indicating the updated value of 'i'
print("\nOriginal list:")
print(nums)

# Print the result of the test function applied to the updated 'nums' list with the updated value of 'i'
print("Check the said list, where the sum of the first i integers is i: i =", i)
print(test(nums, 2))

Sample Output:

Original list:
[0, 1, 2, 3, 4, 5]
Check the said list, where the sum of the first i integers is i: i =  1
False

Original list:
[0, 1, 2, 3, 4, 5]
Check the said list, where the sum of the first i integers is i: i =  3
True

Original list:
[1, 1, 1, 1, 1, 1]
Check the said list, where the sum of the first i integers is i: i =  6
True

Original list:
[2, 2, 2, 2, 2]
Check the said list, where the sum of the first i integers is i: i =  2
False

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to check if the cumulative sum of the first i elements of a list equals i for each i, using iterative summation.
Write a Python program that uses list slicing to verify that the sum of the first i numbers equals i for every valid i in the list.
Write a Python program to determine if a list of integers satisfies the condition by computing the cumulative sum and comparing to an arithmetic series.
Write a Python program to implement the check recursively by verifying the condition for the first element and then for the remainder of the list.

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Python Code Editor :

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