started with the TicTacToe_MinMax Project. Finished the rendering of the game.

TODO: Make a playable version and add MinMax

CodingChallanges/src/numbers/ValidateCreditCard.java

@@ -0,0 +1,38 @@
+package numbers;
+
+// Link: https://edabit.com/challenge/RvxGLMzoPoBgXhcaC
+
+public class ValidateCreditCard {
+
+    public static boolean validateCard(long num) {
+
+        if ((num+"").length()<14 || (num+"".length()<20)){
+            return false;
+        }
+
+        int checkDigit = Integer.parseInt((num+"").substring((num+"").length()-1));
+
+        int[] numInArray = new int [(num+"").length()-1];
+
+        for (int i = 1; i < numInArray.length+1; i++){
+            numInArray[i-1] = Integer.parseInt((num+"").substring((num+"").length()-i-1, (num+"").length()-i));
+            if (i % 2 == 1){
+                numInArray[i-1] *= 2;
+                if (numInArray[i-1]>9){
+                    numInArray[i-1] = (numInArray[i-1]/10) + (numInArray[i-1]-10);
+                }
+            }
+        }
+
+        int sum = 0;
+        for (int i = 0; i < numInArray.length; i++){
+            sum += numInArray[i];
+        }
+        return 10 - (sum-((sum/10)*10)) == checkDigit;
+    }
+
+    public static void main(String[] args) {
+        System.out.println(validateCard(1234567890123456L));
+    }
+
+}