Detect Capital – Leetcode #520

This problem is from Leetcode – Detect Capital. Problem statement is as below:

We define the usage of capitals in a word to be right when one of the following cases holds:

• All letters in this word are capitals, like "USA".
• All letters in this word are not capitals, like "leetcode".
• Only the first letter in this word is capital, like "Google".

Given a string word, return true if the usage of capitals in it is right.

Solution

To determine if the usage of capitals in a given word is correct according to the specified rules, we can implement a function that checks the following conditions:

1. All letters are uppercase.
2. All letters are lowercase.
3. Only the first letter is uppercase, and the rest are lowercase.

See the code sample below:

public boolean detectCapitalUse(String word) {

		Boolean isCapital = false;

		// check if all chars are lowercase
		if(word.equals(word.toLowerCase())) {

			return true;
		}

		// check if all chars are uppercase
		else if(word.equals(word.toUpperCase())) {

			return true;
		}

		// check if first char is uppercase and rest are lowercase
		if(Character.isUpperCase(word.charAt(0)))  {

			String str = word.substring(1, word.length());

			if(str.equals(str.toLowerCase())) {

				return true;
			}
		}


		return isCapital;
	}

You can checkout the code from Github here: Detect Caital – First Approach. See the performance of this approach below: