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# Python: Find the h-index, the largest positive number h such that h occurs in the sequence at least h times

## Python Programming Puzzles: Exercise-49 with Solution

Write a Python program to find the h-index, the largest positive number h such that h occurs in the sequence at least h times. If there is no such positive number return h = -1.

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

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

Input:
[3, 1, 4, 17, 5, 17, 2, 1, 41, 32, 2, 5, 5, 5, 5]
Output:
5

Visual Presentation:

Sample Solution:

Python Code:

# Define a function named 'test' that takes a list of numbers 'nums' as input
def test(nums):
# Calculate the h-index, which is the largest positive number h
# such that h occurs in the sequence at least h times
return max([-1] + [i for i in nums if i > 0 and nums.count(i) >= i])

# Assign a specific list of numbers to the variable 'nums'
nums =  [1, 2, 2, 3, 3, 4, 4, 4, 4]
# Print a message indicating the original list of numbers
print("Original list of numbers:")
# Print the original list of numbers
print(nums)
# Print a message indicating the h-index calculation
print("h-index, the largest positive number h such that h occurs in the said sequence at least h times:")
# Print the result of the test function applied to 'nums'
print(test(nums))

# Assign another specific list of numbers to the variable 'nums'
nums =  [1,2,2,3,4,5,6]
# Print a message indicating the original list of numbers
print("\nOriginal list of numbers:")
# Print the original list of numbers
print(nums)
# Print a message indicating the h-index calculation
print("h-index, the largest positive number h such that h occurs in the said sequence at least h times:")
# Print the result of the test function applied to 'nums'
print(test(nums))

# Assign another specific list of numbers to the variable 'nums'
nums = [3, 1, 4, 17, 5, 17, 2, 1, 41, 32, 2, 5, 5, 5, 5]
# Print a message indicating the original list of numbers
print("\nOriginal list of numbers:")
# Print the original list of numbers
print(nums)
# Print a message indicating the h-index calculation
print("h-index, the largest positive number h such that h occurs in the said sequence at least h times:")
# Print the result of the test function applied to 'nums'
print(test(nums))

Sample Output:

Original list of numbers:
[1, 2, 2, 3, 3, 4, 4, 4, 4]
h-index, the largest positive number h such that h occurs in the said sequence at least h times:
4

Original list of numbers:
[1, 2, 2, 3, 4, 5, 6]
h-index, the largest positive number h such that h occurs in the said sequence at least h times:
2

Original list of numbers:
[3, 1, 4, 17, 5, 17, 2, 1, 41, 32, 2, 5, 5, 5, 5]
h-index, the largest positive number h such that h occurs in the said sequence at least h times:
5

Flowchart:

Python Code Editor :

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