230509 멀쩡한 사각형

public static long solution(int w, int h) {
    long area = (long) w * h;
    long gcd = calculateGcd(w, h);
    long overlappedArea = (w / gcd) + (h / gcd) - 1;
    return area - gcd * overlappedArea;
}

public static long calculateGcd(long a, long b) {
    if (b == 0) {
        return a;
    }
    return calculateGcd(b, a % b);
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/62048