Detect Capital

Problem Statement

In the task at hand, we are given a word, and the objective is to determine whether the usage of capital letters within this word adheres to one of three specified criteria:

1. All characters in the word are uppercase, such as in "USA".
2. All characters are lowercase, as seen in "vultr".
3. Only the initial character of the word is uppercase, illustrated by "Google".

The function should return true if the word's capitalization pattern matches any of the above conditions, otherwise false.

Examples

Example 1

Input:

word = "USA"

Output:

true

Example 2

Input:

word = "FlaG"

Output:

false

Constraints

• 1 <= word.length <= 100
• word consists of lowercase and uppercase English letters.

Approach and Intuition

To solve this problem, we can observe that:

1. If the word is entirely uppercase, such as "USA", a simple check of the word against its uppercased version will confirm this condition.
2. If the word is completely lowercase, like "vultr", comparing the word to its lowercased form will help ascertain this pattern.
3. If only the first letter of the word is uppercase, we can verify this by ensuring that the first character of the word when capitalized remains the same while the rest of the word matches its lowercased form.

Let’s break down the solution steps based on the given examples and the defined constraints:

• Example 1 ("USA"):

  • The word is all uppercase, which matches the first condition.
  • As a result, we would return true.

• Example 2 ("FlaG"):

  • Here, the first letter is uppercase but not all the other letters are lowercase. Therefore, this does not precisely match any of the three described conditions.
  • Hence, the function should return false.

Considering the constraints provided (word length and character types), this problem can be approached efficiently using simple string methods available in most programming languages, allowing for an approach that operates within O(n) time complexity, where n is the length of the string. This ensures that even for the longest possible string of 100 characters, the solution remains computationally feasible.

Solutions

class Solution {
    public boolean isCapitalUsageValid(String text) {
        return text.matches("[A-Z]*|.[a-z]*");
    }
}