IO good enough

src/player/Human.java

@@ -1,6 +1,9 @@
 package player;
 
 import java.util.Scanner;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.Arrays;
 
 public class Human implements Player {
 
@@ -17,8 +20,18 @@ public class Human implements Player {
 
     @Override
     public int move(int[][] board) {
-        System.out.print("Choose a move: ");
-        return sc.nextInt();
+        Set<Integer> options = new HashSet<>(Arrays.asList(0,1,2,3,4,5,6));
+        for (Integer i: new HashSet<Integer>(options)) {
+            if (board[i][0] != 0) {
+                options.remove(i);
+            }
+        }
+        int choice = -1;
+        while (!options.contains(new Integer(choice))) {
+            System.out.print("Choose a move from " + options + ": ");
+            choice = sc.nextInt();
+        }
+        return choice;
     }
 
     @Override