Hey guys,

I am solving this challenge **Data Structures: Find the Minimum and Maximum Height of a Binary Search Tree**

Here’s my code

```
var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
function Node(value) {
this.value = value;
this.left = null;
this.right = null;
}
function BinarySearchTree() {
this.root = null;
// change code below this line
// change code above this line
this.findMinHeight = function(root = this.root) {
// empty tree.
if(root === null) {
return -1;
}
// leaf node.
if(root.left === null && root.right === null) {
return 0;
}
if(root.left === null){
return this.findMinHeight(root.right) + 1;
}
if(root.right === null){
return this.findMinHeight(root.left) + 1;
}
const lHeight = this.findMinHeight(root.left);
const rHeight = this.findMinHeight(root.right);
return Math.min(lHeight, rHeight) + 1;
};
this.findMaxHeight = function(root = this.root) {
// empty tree.
if(root === null) {
return -1;
}
// leaf node.
if(root.left === null && root.right === null) {
return 0;
}
if(root.left === null){
return this.findMaxHeight(root.right) + 1;
}
if(root.right === null){
return this.findMaxHeight(root.left) + 1;
}
const lHeight = this.findMaxHeight(root.left);
const rHeight = this.findMaxHeight(root.right);
return Math.max(lHeight, rHeight) + 1;
};
this.isBalanced = function(root = this.root) {
if(root === null) {
return true;
}
if(root.left === null && root.right === null){
return true;
}
if(root.left === null) {
return this.findMaxHeight(root.right) <= 0;
}
if(root.right === null) {
return this.findMaxHeight(root.left) <= 0;
}
const lHeight = this.findMaxHeight(root.left);
const rHeight = this.findMaxHeight(root.right);
if(Math.abs(lHeight - rHeight) > 1){
return false;
}
return this.isBalanced(root.left) && this.isBalanced(root.right);
};
}
```

Everything is going find except `isBalanced`

function. I am pretty much sure the logic I have written is correct. But I don’t know why test suit is failing. When I printed the root using `displayTree`

function this the tree I have got.

```
{
"value": 4,
"left": {
"value": 1,
"left": null,
"right": null
},
"right": {
"value": 7,
"left": null,
"right": {
"value": 87,
"left": {
"value": 34,
"left": {
"value": 8,
"left": null,
"right": null
},
"right": {
"value": 45,
"left": null,
"right": {
"value": 73,
"left": null,
"right": null
}
}
},
"right": null
}
}
}
```

To me, it looks like this tree is not balanced. So function should return `false`

and it does so. But I don’t know why when I run the test suits, it says

```
// running test
The isBalanced method returns true if the tree is a balanced binary search tree.
// tests completed`
```

Can anyone please help me with this? Thanks.