Add HW01 exercises

HW01/PrimeFactors_05.java

@@ -0,0 +1,35 @@
+import java.util.Scanner;
+import java.util.ArrayList;
+
+public class PrimeFactors {
+    public static ArrayList<Integer> Factors(int num){
+        ArrayList<Integer>  factors = new ArrayList<>();
+
+        if (num <= 1){
+            System.out.println("no prime factor!.");
+        }
+
+        while (num%2 == 0){
+            factors.add(2);
+            num /= 2;
+        }
+        for(int i = 3; i*i <= num; i+=2){
+            while (num%i == 0){
+                factors.add(i);
+                num /= i;
+            }
+        }
+        if (num > 1 ){
+            factors.add(num);
+        }
+        return factors;
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int number = sc.nextInt();
+        ArrayList<Integer> factors = Factors(number);
+         if (!factors.isEmpty()){
+             System.out.println("factors =  "+ factors);
+         }
+    }
+}