Simplify implementation.

Author: Schwarf

data_structures/source/test/trees/binary_trees/test_height_balanced_binary_tree.cpp

@@ -24,6 +24,11 @@ TEST_F(SetupBinaryTree, EvenOddTreeIsNotBalanced) {
     EXPECT_FALSE(height_balanced_binary_tree(root));
 }
 
+TEST_F(SetupBinaryTree, EvenOddTree2IsNotBalanced) {
+    auto root = even_odd_tree2();
+    EXPECT_FALSE(height_balanced_binary_tree(root));
+}
+
 TEST_F(SetupBinaryTree, TwoNodesIsBalanced) {
     auto root = new TreeNode<int>(1);
     root->right = new TreeNode<int>(2);

data_structures/source/trees/binary_trees/height_balanced_binary_tree.h

@@ -17,10 +17,7 @@ int balanced_height(TreeNode<T>* node)
     if(!node)
         return 0;
     const int left_height = balanced_height(node->left);
-    if(left_height == -1)
-        return -1;
     const int right_height = balanced_height(node->right);
-
     if (std::abs(left_height - right_height) > 1)
         return -1;
     return 1 + std::max(left_height, right_height);