题解 | #求最小公倍数#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        ArrayList<Integer> factorList1 = new ArrayList<>();
        ArrayList<Integer> factorList2 = new ArrayList<>();
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        getFactors(num1, factorList1);
        getFactors(num2, factorList2);

        //判断特殊条件 两个数能直接整除
        if (num2 % num1 == 0) {
            System.out.println(num2);
            return;
        }
        if (num1 % num2 == 0) {
            System.out.println(num1);
            return;
        }
        //判断特殊条件 两个数都是素数
        if (factorList1.size() == 0 || factorList2.size() == 0) {
            System.out.println(num1 * num2);
            return;
        }

        int result = 1;

        //去除公因数(逻辑删除：将要清除位置的值置为1),将公因数乘入result
        for (int i = 0; i < factorList1.size(); i++) {
            int factor = factorList1.get(i);
            if (factorList2.contains(factor)) {
                int index = factorList2.indexOf(factor);
                factorList1.set(i, 1);
                factorList2.set(index, 1);
                result *= factor;
            }
        }

        //遍历因数数组，将非公因数乘入result
        for (int i = 0; i < factorList1.size(); i++) {
            result *= factorList1.get(i);
        }
        for (int i = 0; i < factorList2.size(); i++) {
            result *= factorList2.get(i);
        }
        System.out.println(result);
    }


    /**
     * 递归得到一个数的因数数组
     */
    public static boolean getFactors(int num, ArrayList<Integer> list) {
        for (int i = 2; i <= Math.sqrt(num); i++) {
            if (num % i == 0) {
                list.add(i);
                if (getFactors(num / i, list)) return true;
            }
        }
        list.add(num);
        return true;
    }
}