Add Tree building

src/Tree.java

@@ -0,0 +1,49 @@
+/**
+ * Created by azael on 20/03/17.
+ */
+public class Tree {
+
+    private Node root;
+    private String exp;
+
+    Tree (String exp){
+        this.exp = exp;
+        root = tree(0);
+    }
+
+    private Node tree(int pos) {
+        char item = exp.charAt(pos);
+
+        if(Expression.isOperator(item)) {
+            if (item == '!'){
+                Node fils = tree(pos+1);
+                Node f =  new Node(null, fils, null, item, 1+fils.getLvl());
+                fils.setFather(f);
+                return f;
+            }
+
+            Node filsG = tree(pos+1);
+            Node filsD = tree(pos+filsG.getLvl());
+            Node f = new Node(null, filsG, filsD, item, filsG.getLvl() + filsD.getLvl()+1);
+            filsG.setFather(f);
+            filsD.setFather(f);
+            return f;
+        } else {
+            return new Node(null, null, null, item, 1);
+        }
+    }
+
+    public void display () {
+        displayNode(root,0);
+    }
+
+    private void displayNode(Node n, int lvl){
+        for (int i = 0; i < lvl; i++)
+            System.out.print("-");
+        n.display();
+        if (n.getLeftChild() != null)
+            displayNode(n.getLeftChild(),lvl+1);
+        if (n.getRigthChild() != null)
+            displayNode(n.getRigthChild(),lvl+1);
+    }
+}