LeetCode 520 Detect Capital in Python | Easy Coding Tutorial for Beginners

Solve LeetCode 520 "Detect Capital" in Python with this beginner-friendly coding tutorial! This problem asks you to check if a word’s capitalization is valid: it must be all capitals (e.g., "USA"), all lowercase (e.g., "leetcode"), or only the first letter capitalized (e.g., "Google"). For example, "FlaG" returns false. We’ll use Python’s built-in string methods like `isupper()`, `islower()`, and `istitle()`, and explore an alternative approach by counting capitals. Perfect for Python learners, coding beginners, or anyone prepping for coding interviews!

🔍 **What You'll Learn:**
- Understanding LeetCode 520’s capitalization rules
- Using Python string methods to check capitalization
- Exploring a manual approach by counting capital letters
- Testing with example cases

💻 **Code Used in This Video:**
class Solution(object):
def detectCapitalUse(self, word):
"""
:type word: str
:rtype: bool
"""
return (
)

# Test cases
solution = Solution()

# Test case 1: All capitals
# All letters are uppercase

# Test case 2: All lowercase
# All letters are lowercase

# Test case 3: First letter capitalized
# First letter is uppercase, rest are lowercase

# Test case 4: Invalid capitalization
# Mixed capitalization that doesn’t fit the rules

# Test case 5: Single letter
# Single letter is always valid (counts as all capitals or title case)

# Alternative: Manual approach by counting capitals
class SolutionManual(object):
def detectCapitalUse(self, word):
"""
:type word: str
:rtype: bool
"""
# Case 1: All capitals (capitals == len(word))
# Case 2: All lowercase (capitals == 0)
# Case 3: First letter capitalized (capitals == 1 and first letter is capital)
return (
capitals == len(word) or
capitals == 0 or
(capitals == 1 and word[0].isupper())
)

solution_manual = SolutionManual()
print("\nManual solution:")

🌟 **Why Solve LeetCode 520?**
This problem is a great introduction to string manipulation and pattern checking in Python, a common topic in coding interviews! The string method solution has a time complexity of O(n), where n is the length of the word, with O(1) space complexity. The manual approach also runs in O(n) time and provides a deeper understanding of the rules. We’ll explore both methods to detect valid capitalization. Master this, and you’ll be ready for more advanced LeetCode challenges!

📚 **Who’s This For?**
- Python beginners learning coding
- Coding enthusiasts tackling LeetCode problems
- Developers prepping for technical interviews

👍 Like, subscribe, and comment: What LeetCode problem should we solve next? Next up: More LeetCode string problems—stay tuned!

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