# Find the Minimum and Maximum Height of a Binary Search Tree

## Solutions

Solution 1 (Click to Show/Hide)
``````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);
};
}
``````