package com.thealgorithms.others;
/**
* @author Marcus
*/
public final class CountWords {
private CountWords() {
}
/**
* Counts the number of words in the input string. Words are defined as sequences of
* characters separated by whitespace.
*
* @param s the input string
* @return the number of words in the input string, or 0 if the string is null or empty
*/
public static int wordCount(String s) {
if (s == null || s.isEmpty()) {
return 0;
}
return s.trim().split("\\s+").length;
}
/**
* Removes all special characters from the input string, leaving only alphanumeric characters
* and whitespace.
*
* @param s the input string
* @return a string containing only alphanumeric characters and whitespace
*/
private static String removeSpecialCharacters(String s) {
StringBuilder sb = new StringBuilder();
for (char c : s.toCharArray()) {
if (Character.isLetterOrDigit(c) || Character.isWhitespace(c)) {
sb.append(c);
}
}
return sb.toString();
}
/**
* Counts the number of words in a sentence, ignoring all non-alphanumeric characters that do
* not contribute to word formation. This method has a time complexity of O(n), where n is the
* length of the input string.
*
* @param s the input string
* @return the number of words in the input string, with special characters removed, or 0 if the string is null
*/
public static int secondaryWordCount(String s) {
if (s == null) {
return 0;
}
return wordCount(removeSpecialCharacters(s));
}
}