Check if lowercase and uppercase characters are in same order in Python

Suppose we have a string with only lowercase or uppercase letters. We need to check whether both lowercase and uppercase letters follow the same order respectively. This means if we extract all lowercase letters and all uppercase letters separately, converting the lowercase sequence to uppercase should match the uppercase sequence.

So, if the input is like s = "piPpIePE", then the output will be True, as the lowercase letters "piepe" when converted to uppercase become "PIEPE", which matches the extracted uppercase sequence "PIEPE".

Algorithm

To solve this, we follow these steps ?

• Initialize empty strings for lowercase and uppercase letters
• Iterate through each character in the string
• If character is uppercase, append to uppercase string
• If character is lowercase, append to lowercase string
• Convert lowercase string to uppercase and compare with uppercase string

Method 1: Using ASCII Values

We can check if a character is uppercase by comparing its ASCII value ?

def solve(s):
    lowercase = ""
    uppercase = ""
    for i in range(len(s)):
        if ord(s[i]) >= 65 and ord(s[i]) <= 90:
            uppercase += s[i]
        else:
            lowercase += s[i]
    to_upper = lowercase.upper()
    return to_upper == uppercase

s = "piPpIePE"
print(solve(s))

True

Method 2: Using Built-in Methods

A cleaner approach using Python's built-in string methods ?

def solve(s):
    lowercase = ""
    uppercase = ""
    for char in s:
        if char.isupper():
            uppercase += char
        else:
            lowercase += char
    return lowercase.upper() == uppercase

s = "piPpIePE"
print(solve(s))

True

Method 3: Using List Comprehension

A more concise solution using list comprehensions ?

def solve(s):
    lowercase = ''.join([char for char in s if char.islower()])
    uppercase = ''.join([char for char in s if char.isupper()])
    return lowercase.upper() == uppercase

# Test with multiple examples
test_cases = ["piPpIePE", "aAbBcC", "aBcDeF", "abcDEF"]

for test in test_cases:
    result = solve(test)
    print(f"'{test}' ? {result}")

'piPpIePE' ? True
'aAbBcC' ? True
'aBcDeF' ? False
'abcDEF' ? False

How It Works

Let's trace through the example "piPpIePE" ?

• Extract lowercase letters: "p", "i", "p", "e" ? "pipe"
• Extract uppercase letters: "P", "I", "P", "E" ? "PIPE"
• Convert lowercase to uppercase: "pipe".upper() ? "PIPE"
• Compare: "PIPE" == "PIPE" ? True

Comparison

Conclusion

Use the built-in method approach for the best balance of readability and performance. The algorithm extracts lowercase and uppercase sequences separately, then compares them after case conversion.