Implement treeSize() and update clearTree()

bintree.c

@@ -78,9 +78,9 @@ void clearTree(TreeNode *root)
         return;
     }
     
-    clearTree(root->right);
     clearTree(root->left);
-    
+    clearTree(root->right);
+
     free(root->data);
     free(root);
     
@@ -89,5 +89,8 @@ void clearTree(TreeNode *root)
 // Returns the number of entries in the tree given by root.
 unsigned int treeSize(const TreeNode *root)
 {
-
+    if(root == NULL){
+        return 0;
+    }
+    return 1 + treeSize(root->left) + treeSize(root->right);
 }