it('can walk a tree in order', function() {
const tree = new BinaryTree(numericalCompare)
tree.insert(3)
tree.insert(4)
tree.insert(1)
tree.insert(2)
const result: any[] = []
walkInOrder(tree, tree.root, n => result.push(n.key))
expect(result).toEqual([1, 2, 3, 4])
})
it('tree height is always max log(n) * 2 and has same black node count', function() {
const numbers = times(Math.random, 100).map(n => Math.floor(n * 100))
const tree = new RBTree(numericalCompare)
let count = 0
for (const n of numbers) {
tree.insert(n)
count++
let minBlackCount = 0
const minNode = min(tree, tree.root)
walkToRoot(tree, minNode, n => {
if (!(n as RBNode<number>).red) {
minBlackCount++
}
})
walkInOrder(tree, tree.root, n => {
if (n.left === tree.nil && n.right === tree.nil) {
let height = 0
let blackCount = 0
walkToRoot(tree, n, n => {
height++
if (!(n as RBNode<number>).red) {
blackCount++
}
})
expect(blackCount).toBe(minBlackCount)
expect(height).toBeLessThan(
Math.floor(Math.log2(count + 1) * 2 + 1),
)
}
})
}
expect(count === numbers.length && count === tree.size()).toBe(true)
const shuffled = shuffle(numbers)
for (const n of shuffled) {
tree.remove(n)
count--
let minBlackCount = 0
const minNode = min(tree, tree.root)
walkToRoot(tree, minNode, n => {
if (!(n as RBNode<number>).red) {
minBlackCount++
}
})
walkInOrder(tree, tree.root, n => {
if (n.left === tree.nil && n.right === tree.nil) {
let height = 0
let blackCount = 0
walkToRoot(tree, n, n => {
height++
if (!(n as RBNode<number>).red) {
blackCount++
}
})
expect(blackCount).toBe(minBlackCount)
expect(height).toBeLessThan(
Math.floor(Math.log2(count + 1) * 2 + 1),
)
}
})
}
})