Create 20. Doubles

Week 2: Methods, strings and lists/20. Doubles

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+Write the method
+
+int doubles(ArrayList<Integer> list1, ArrayList<Integer> list2)
+
+which takes two integer reading lists as parameters. 
+The method returns the number of elements found in both list 1 and list 2.
+
+
+Example method call:
+public static void main(String[] args){
+    ArrayList<Integer> list1 = new ArrayList<>();
+    ArrayList<Integer> list2 = new ArrayList<>();
+
+    list1.add(1);
+    list1.add(2);
+    list1.add(3);
+
+    list2.add(3);
+    list2.add(4);
+    list2.add(5);
+    list2.add(6);
+
+    int t = doubles(list1, list2);
+    System.out.println("Doubles: " + t);
+}
+
+Program outputs:
+Doubles: 1
+
+
+
+
+
+
+
+
+
+
+import java.util.Random;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
+public class Test{
+    public static void main(String[] args){
+        final Random r = new Random();
+        
+        test(new int[]{1,2,3,4,5,6,7,8}, new int[]{5,6,7,8,9,10,11,12});
+        test(new int[]{10,20,30,40,50,60,70}, new int[]{25,30,35,40,45,50});
+        test(new int[]{1,9,2,8,3,7,4,6}, new int[]{10,11,12,3,14,15,16,7,4,99,1,98,2});
+    }
+    
+    public static void test(int[] l1, int[] l2) {
+        ArrayList<Integer> list1 = new ArrayList<>();
+        for (int a : l1) {
+            list1.add(a);
+        }
+        
+        ArrayList<Integer> list2 = new ArrayList<>();
+        for (int a : l2) {
+            list2.add(a);
+        }
+        
+        System.out.println("Testing with lists ");
+        System.out.println("" + list1);
+        System.out.println("and");
+        System.out.println("" + list2);
+        System.out.println("Doubles: " + doubles(list1, list2));
+        System.out.println("");
+    }
+    
+
+
+    //ADD
+    //ASSUME BOTH list1, list2 do not contain dupe elements
+    public static int doubles(ArrayList<Integer> list1, ArrayList<Integer> list2) {
+        int count = 0;
+
+        // // check Double dtype of each element
+        // for (int i = 0; i < list1.size(); i++) {
+        //     if (list1.get(i) instanceof Double) { 
+        //         count++;
+        //     }
+        // }
+        // for (int i = 0; i < list2.size(); i++) {
+        //     if (list2.get(i) instanceof Double) { 
+        //         count++;
+        //     }
+        // }
+
+        for (int i: list1) {
+            if (list2.contains(i)) {
+                count++;
+            }
+        }
+        return count;
+    }
+
+
+
+
+
+}
+
+
+
+
+
+
+
+
+Testing with lists 
+[1, 2, 3, 4, 5, 6, 7, 8]
+and
+[5, 6, 7, 8, 9, 10, 11, 12]
+Doubles: 4
+
+Testing with lists 
+[10, 20, 30, 40, 50, 60, 70]
+and
+[25, 30, 35, 40, 45, 50]
+Doubles: 3
+
+Testing with lists 
+[1, 9, 2, 8, 3, 7, 4, 6]
+and
+[10, 11, 12, 3, 14, 15, 16, 7, 4, 99, 1, 98, 2]
+Doubles: 5
+
+