public class ABCWordCheck {
/**
Function: isABCWord
Purpose:
Check whether the letters 'a', 'b', and 'c' appear in the word
in alphabetical order (a → b → c). They do NOT need to be consecutive.
Efficient Algorithm (O(n)):
- Convert the word to lowercase once.
- Scan characters from left to right.
- Track whether 'a' has appeared, then 'b', then 'c'.
- If 'b' appears before 'a', or 'c' appears before 'b', the order is invalid.
- If we eventually see 'c' after both 'a' and 'b', return true.
Notes:
- Case-insensitive.
- Uses only built-in Java methods.
*/
public static boolean isABCWord(String word) {
String lower = word.toLowerCase();
boolean seenA = false;
boolean seenB = false;
for (int i = 0; i < lower.length(); i++) {
char c = lower.charAt(i);
if (c == 'a') {
seenA = true;
} else if (c == 'b') {
if (!seenA) return false; // 'b' before 'a' → invalid
seenB = true;
} else if (c == 'c') {
if (!seenB) return false; // 'c' before 'b' → invalid
return true; // Found a → b → c in order
}
}
return false; // Did not find all three in order
}
public static void main(String[] args) {
String word = "algebraic"; // Example word
System.out.println("Word: " + word);
if (isABCWord(word)) {
System.out.println("Result: This IS an ABC word.");
} else {
System.out.println("Result: This is NOT an ABC word.");
}
}
}
/*
run:
Word: algebraic
Result: This IS an ABC word.
*/
