String Without AAA or BBB

LeetCode Q 984 - String Without AAA or BBB

Given two integers A and B, return any string S such that:

• S has length A + B and contains exactly A ‘a’ letters, and exactly B ‘b’ letters;
• The substring ‘aaa’ does not occur in S;
• The substring ‘bbb’ does not occur in S.

Example 1: Input: A = 1, B = 2 ; Output: "abb"
Explanation: “abb”, “bab” and “bba” are all correct answers.

Example 2: Input: A = 4, B = 1 ; Output: "aabaa"

Note:

• 0 <= A <= 100
• 0 <= B <= 100
• It is guaranteed such an S exists for the given A and B.

Solution

Code:

public String strWithout3a3b(int A, int B) {

	StringBuilder sb = new StringBuilder();

	while (A + B != 0) {

		String str = sb.toString();

		if (str.endsWith("aa")) {
			sb.append('b'); B--;
		} else if (str.endsWith("bb")) {
			sb.append('a'); A--;
		} else if (A > B) {
			sb.append('a'); A--;
		} else {
			sb.append('b'); B--;
		}
	}

	return sb.toString();
}