Python program to find maximum uppercase run?

Finding the longest consecutive sequence of uppercase letters in a string is a common text processing task. This problem appears in data analysis, text validation, and pattern extraction scenarios. We'll explore two efficient approaches: the iterative method and regular expressions.

Approaches

To find the maximum uppercase run in Python, we can use two methods:

• Using the iterative method

• Using regular expressions

Let's examine both approaches in detail.

Method 1: Using Iterative Approach

The iterative method scans the string character by character, tracking the current run of uppercase letters and comparing it with the maximum run found so far.

Algorithm

The steps to find the maximum uppercase run are:

Step 1 ? Initialize maximum run length as 0 and current run length as 0.

Step 2 ? Iterate through each character in the input string.

Step 3 ? If the character is uppercase, append it to the current run and increment the length.

Step 4 ? If the character is not uppercase, compare current run with maximum run and update if longer.

Step 5 ? Reset current run variables and continue.

Step 6 ? Return the maximum run and its length.

Example

def find_max_uppercase_run_iterative(string):
    max_run_length = 0
    current_run_length = 0
    max_run = ""
    current_run = ""

    for char in string:
        if char.isupper():
            current_run += char
            current_run_length += 1
        else:
            if current_run_length > max_run_length:
                max_run_length = current_run_length
                max_run = current_run
            current_run = ""
            current_run_length = 0

    # Check final run in case string ends with uppercase
    if current_run_length > max_run_length:
        max_run_length = current_run_length
        max_run = current_run

    return max_run, max_run_length


input_string = "PrograMMINGisFUN"
max_run, max_run_length = find_max_uppercase_run_iterative(input_string)

print("Input String:", input_string)
print("Maximum Uppercase Run:", max_run)
print("Maximum Uppercase Run Length:", max_run_length)

The output of the above code is ?

Input String: PrograMMINGisFUN
Maximum Uppercase Run: MMING
Maximum Uppercase Run Length: 5

Method 2: Using Regular Expressions

The regular expression approach uses pattern matching to find all consecutive uppercase sequences, then selects the longest one using the max() function.

Algorithm

The steps using regular expressions are:

Step 1 ? Import the regular expression module.

Step 2 ? Define pattern [A-Z]+ to match consecutive uppercase letters.

Step 3 ? Use re.findall() to find all matches in the input string.

Step 4 ? Find the longest match using max() with key=len.

Step 5 ? Return the maximum run and its length.

Example

import re

def find_max_uppercase_run_regex(string):
    matches = re.findall(r'[A-Z]+', string)
    max_run = max(matches, key=len) if matches else ""
    max_run_length = len(max_run)
    return max_run, max_run_length

input_string = "PrograMMINGisFUN"
max_run, max_run_length = find_max_uppercase_run_regex(input_string)

print("Input String:", input_string)
print("Maximum Uppercase Run:", max_run)
print("Maximum Uppercase Run Length:", max_run_length)

The output of the above code is ?

Input String: PrograMMINGisFUN
Maximum Uppercase Run: MMING
Maximum Uppercase Run Length: 5

Comparison

Conclusion

Both methods effectively find the maximum uppercase run in a string. The iterative approach offers better memory efficiency, while regular expressions provide more concise and readable code. Choose based on your specific requirements for performance versus code simplicity.