Skip to main content

TreeSet

data-structure-typed

data-structure-typed / TreeSet

Class: TreeSet<K, R>

Defined in: data-structures/binary-tree/tree-set.ts:26

An ordered Set backed by a red-black tree.

  • Iteration order is ascending by key.
  • No node exposure: all APIs use keys only.

Example​

// Set multiple key-value pairs
 const ts = new TreeSet<number, string>();
    ts.setMany([[1, 'a'], [2, 'b'], [3, 'c']]);
    console.log(ts.size); // 3;

Type Parameters​

K​

K = any

R​

R = K

Implements​

  • Iterable<K>

Constructors​

Constructor​

new TreeSet<K, R>(elements?, options?): TreeSet<K, R>;

Defined in: data-structures/binary-tree/tree-set.ts:46

Create a TreeSet from an iterable of keys or raw elements.

Parameters​

elements?​

Iterable<K, any, any> | Iterable<R, any, any>

Iterable of keys, or raw elements if toElementFn is provided.

options?​

TreeSetOptions<K, R> = {}

Configuration options including optional toElementFn to transform raw elements.

Returns​

TreeSet<K, R>

Throws​

When using the default comparator and encountering unsupported key types, or invalid keys (e.g. NaN, invalid Date).

Example​

// Standard usage with keys
const set = new TreeSet([3, 1, 2]);

// Using toElementFn to transform raw objects
const users = [{ id: 3, name: 'Alice' }, { id: 1, name: 'Bob' }];
const set = new TreeSet<number, User>(users, { toElementFn: u => u.id });

Accessors​

size​

Get Signature​

get size(): number;

Defined in: data-structures/binary-tree/tree-set.ts:101

Number of elements in the set.

Returns​

number

Methods​

add()​

add(key): this;

Defined in: data-structures/binary-tree/tree-set.ts:458

Add a key to the set (no-op if already present).

Parameters​

key​

K

Returns​

this

Remarks​

Expected time O(log n)

Example​

// Unique tags with sorted order
 const tags = new TreeSet<string>(['javascript', 'typescript', 'react', 'typescript', 'node']);

    // Duplicates removed, sorted alphabetically
    console.log([...tags]); // ['javascript', 'node', 'react', 'typescript'];
    console.log(tags.size); // 4;

    tags.add('angular');
    console.log(tags.first()); // 'angular';
    console.log(tags.last()); // 'typescript';

ceiling()​

ceiling(key): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:3390

Smallest key that is >= the given key.

Parameters​

key​

K

Returns​

K | undefined

Example​

// Finding nearest available time slot
 // Available appointment times (minutes from midnight)
    const slots = new TreeSet<number>([540, 600, 660, 720, 840, 900]);

    // Customer wants something around 10:30 (630 min)
    const nearest = slots.ceiling(630);
    console.log(nearest); // 660; // 11:00 AM

    // What's the latest slot before 2:00 PM (840)?
    const before2pm = slots.lower(840);
    console.log(before2pm); // 720; // 12:00 PM

    // Book the 11:00 slot
    slots.delete(660);
    console.log(slots.ceiling(630)); // 720;

clear()​

clear(): void;

Defined in: data-structures/binary-tree/tree-set.ts:987

Remove all keys.

Returns​

void

Example​

// Remove all
 const ts = new TreeSet<number>([1, 2]);
      ts.clear();
      console.log(ts.isEmpty()); // true;

clone()​

clone(): TreeSet<K>;

Defined in: data-structures/binary-tree/tree-set.ts:4167

Creates a shallow clone of this set.

Returns​

TreeSet<K>

Remarks​

Time O(n log n), Space O(n)

Example​

// Deep clone
 const ts = new TreeSet<number>([1, 2, 3]);
      const copy = ts.clone();
      copy.delete(1);
      console.log(ts.has(1)); // true;

delete()​

delete(key): boolean;

Defined in: data-structures/binary-tree/tree-set.ts:820

Delete a key.

Parameters​

key​

K

Returns​

boolean

true if the key existed; otherwise false.

Remarks​

Expected time O(log n)

Example​

// Removing elements while maintaining order
 const nums = new TreeSet<number>([1, 3, 5, 7, 9]);

    console.log(nums.delete(5)); // true;
    console.log(nums.delete(5)); // false; // already gone
    console.log([...nums]); // [1, 3, 7, 9];

entries()​

entries(): IterableIterator<[K, K]>;

Defined in: data-structures/binary-tree/tree-set.ts:1483

Iterate over [value, value] pairs (native Set convention).

Note: TreeSet stores only keys internally; [k, k] is created on-the-fly during iteration.

Returns​

IterableIterator<[K, K]>

Example​

// Iterate entries
 const ts = new TreeSet<number>([3, 1, 2]);
      console.log([...ts.entries()].map(([k]) => k)); // [1, 2, 3];

every()​

every(callbackfn, thisArg?): boolean;

Defined in: data-structures/binary-tree/tree-set.ts:2341

Test whether all values satisfy a predicate.

Parameters​

callbackfn​

TreeSetElementCallback<K, boolean, TreeSet<K, K>>

thisArg?​

unknown

Returns​

boolean

Remarks​

Time O(n), Space O(1)

Example​

// Test all
 const ts = new TreeSet<number>([2, 4, 6]);
      console.log(ts.every(k => k > 0)); // true;

filter()​

filter(callbackfn, thisArg?): TreeSet<K>;

Defined in: data-structures/binary-tree/tree-set.ts:2001

Create a new TreeSet containing only values that satisfy the predicate.

Parameters​

callbackfn​

TreeSetElementCallback<K, boolean, TreeSet<K, K>>

thisArg?​

unknown

Returns​

TreeSet<K>

Remarks​

Time O(n log n) expected, Space O(n)

Example​

// Filter
 const ts = new TreeSet<number>([1, 2, 3, 4, 5]);
      const evens = ts.filter(k => k % 2 === 0);
      console.log([...evens]); // [2, 4];

find()​

find(callbackfn, thisArg?): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:2682

Find the first value that satisfies a predicate.

Parameters​

callbackfn​

TreeSetElementCallback<K, boolean, TreeSet<K, K>>

thisArg?​

unknown

Returns​

K | undefined

Remarks​

Time O(n), Space O(1)

Example​

// Find entry
 const ts = new TreeSet<number>([1, 2, 3]);
      const found = ts.find(k => k === 2);
      console.log(found); // 2;

first()​

first(): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:3090

Smallest key in the set.

Returns​

K | undefined

Example​

// Student grade ranking with custom comparator
 interface Student {
      name: string;
      gpa: number;
    }

    const ranking = new TreeSet<Student>(
      [
        { name: 'Alice', gpa: 3.8 },
        { name: 'Bob', gpa: 3.5 },
        { name: 'Charlie', gpa: 3.9 },
        { name: 'Diana', gpa: 3.5 }
      ],
      { comparator: (a, b) => b.gpa - a.gpa || a.name.localeCompare(b.name) }
    );

    // Sorted by GPA descending, then name ascending
    const names = [...ranking].map(s => s.name);
    console.log(names); // ['Charlie', 'Alice', 'Bob', 'Diana'];

    // Top student
    console.log(ranking.first()?.name); // 'Charlie';

    // Filter students with GPA >= 3.8
    const honors = ranking.filter(s => s.gpa >= 3.8);
    console.log(honors.toArray().map(s => s.name)); // ['Charlie', 'Alice'];

floor()​

floor(key): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:3536

Largest key that is <= the given key.

Parameters​

key​

K

Returns​

K | undefined

Example​

// Largest element ≤ target
 const breakpoints = new TreeSet<number>([320, 768, 1024, 1280, 1920]);

    // Current width is 800 → which breakpoint applies?
    console.log(breakpoints.floor(800)); // 768;
    console.log(breakpoints.floor(1024)); // 1024; // exact match
    console.log(breakpoints.floor(100)); // undefined;

forEach()​

forEach(cb, thisArg?): void;

Defined in: data-structures/binary-tree/tree-set.ts:1655

Visit each value in ascending order.

Callback follows native Set convention: (value, value2, set).

Parameters​

cb​

(value, value2, set) => void

thisArg?​

unknown

Returns​

void

Example​

// Execute for each
 const ts = new TreeSet<number>([3, 1, 2]);
      const keys: number[] = [];
      ts.forEach(k => keys.push(k));
      console.log(keys); // [1, 2, 3];

has()​

has(key): boolean;

Defined in: data-structures/binary-tree/tree-set.ts:639

Test whether a key exists.

Parameters​

key​

K

Returns​

boolean

Remarks​

Expected time O(log n)

Example​

// Checking membership in a sorted collection
 const allowed = new TreeSet<string>(['admin', 'editor', 'viewer']);

    console.log(allowed.has('admin')); // true;
    console.log(allowed.has('guest')); // false;

higher()​

higher(key): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:3680

Smallest key that is > the given key.

Parameters​

key​

K

Returns​

K | undefined

Example​

// Smallest element strictly > target
 const levels = new TreeSet<number>([1, 5, 10, 25, 50, 100]);

    console.log(levels.higher(10)); // 25;
    console.log(levels.higher(100)); // undefined;

isEmpty()​

isEmpty(): boolean;

Defined in: data-structures/binary-tree/tree-set.ts:264

Whether the set is empty.

Returns​

boolean

Example​

// Check empty
 console.log(new TreeSet().isEmpty()); // true;

keys()​

keys(): IterableIterator<K>;

Defined in: data-structures/binary-tree/tree-set.ts:1151

Iterate over keys in ascending order.

Returns​

IterableIterator<K>

Example​

// Get sorted keys
 const ts = new TreeSet<number>([30, 10, 20]);
      console.log([...ts.keys()]); // [10, 20, 30];

last()​

last(): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:3136

Largest key in the set.

Returns​

K | undefined

Example​

// Get the maximum element
 const temps = new TreeSet<number>([18, 22, 15, 30, 25]);
    console.log(temps.last()); // 30;
    console.log(temps.first()); // 15;

lower()​

lower(key): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:3824

Largest key that is < the given key.

Parameters​

key​

K

Returns​

K | undefined

Example​

// Largest element strictly < target
 const tiers = new TreeSet<number>([100, 200, 500, 1000]);

    console.log(tiers.lower(500)); // 200;
    console.log(tiers.lower(100)); // undefined;

map()​

map<MK>(
   callbackfn, 
   options?, 
thisArg?): TreeSet<MK>;

Defined in: data-structures/binary-tree/tree-set.ts:1823

Create a new TreeSet by mapping each value to a new key.

This mirrors RedBlackTree.map: mapping produces a new ordered container.

Type Parameters​

MK​

MK

Parameters​

callbackfn​

TreeSetElementCallback<K, MK, TreeSet<K, K>>

options?​

Omit<TreeSetOptions<MK, MK>, "toElementFn"> & object = {}

thisArg?​

unknown

Returns​

TreeSet<MK>

Remarks​

Time O(n log n) expected, Space O(n)

Example​

// Transform
 const ts = new TreeSet<number>([1, 2, 3]);
      const doubled = ts.map(k => k * 2);
      console.log([...doubled]); // [2, 4, 6];

pollFirst()​

pollFirst(): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:3184

Remove and return the smallest key.

Returns​

K | undefined

Example​

// Remove and return minimum
 const queue = new TreeSet<number>([5, 1, 8, 3]);

    console.log(queue.pollFirst()); // 1;
    console.log(queue.pollFirst()); // 3;
    console.log(queue.size); // 2;

pollLast()​

pollLast(): K | undefined;

Defined in: data-structures/binary-tree/tree-set.ts:3234

Remove and return the largest key.

Returns​

K | undefined

Example​

// Remove and return maximum
 const stack = new TreeSet<number>([10, 20, 30]);

    console.log(stack.pollLast()); // 30;
    console.log(stack.size); // 2;

print()​

print(): void;

Defined in: data-structures/binary-tree/tree-set.ts:3019

Print a human-friendly representation.

Returns​

void

Remarks​

Time O(n), Space O(n)

Example​

// Display tree
 const ts = new TreeSet<number>([1, 2, 3]);
      expect(() => ts.print()).not.toThrow();

rangeSearch()​

rangeSearch(range, options?): K[];

Defined in: data-structures/binary-tree/tree-set.ts:3982

Return all keys in a given range.

Parameters​

range​

[K, K]

[low, high]

options?​

TreeSetRangeOptions = {}

Inclusive/exclusive bounds (defaults to inclusive).

Returns​

K[]

Example​

// IP address blocklist with range checking
 // Simplified: use numeric IP representation
    const blocklist = new TreeSet<number>([
      167772160, // 10.0.0.0
      167772416, // 10.0.1.0
      167772672, // 10.0.2.0
      167773184  // 10.0.4.0
    ]);

    // Check if any blocked IP is in range 10.0.1.0 - 10.0.3.0
    const inRange = blocklist.rangeSearch([167772416, 167772928]);
    console.log(inRange); // [167772416, 167772672];

    // Quick membership check
    console.log(blocklist.has(167772416)); // true;
    console.log(blocklist.has(167772800)); // false;

reduce()​

reduce<A>(callbackfn, initialValue): A;

Defined in: data-structures/binary-tree/tree-set.ts:2175

Reduce values into a single accumulator.

Type Parameters​

A​

A

Parameters​

callbackfn​

TreeSetReduceCallback<K, A, TreeSet<K, K>>

initialValue​

A

Returns​

A

Remarks​

Time O(n), Space O(1)

Example​

// Aggregate
 const ts = new TreeSet<number>([1, 2, 3]);
      const sum = ts.reduce((acc, k) => acc + k, 0);
      console.log(sum); // 6;

some()​

some(callbackfn, thisArg?): boolean;

Defined in: data-structures/binary-tree/tree-set.ts:2511

Test whether any value satisfies a predicate.

Parameters​

callbackfn​

TreeSetElementCallback<K, boolean, TreeSet<K, K>>

thisArg?​

unknown

Returns​

boolean

Remarks​

Time O(n), Space O(1)

Example​

// Test any
 const ts = new TreeSet<number>([1, 3, 5]);
      console.log(ts.some(k => k === 3)); // true;

toArray()​

toArray(): K[];

Defined in: data-structures/binary-tree/tree-set.ts:2854

Materialize the set into an array of keys.

Returns​

K[]

Remarks​

Time O(n), Space O(n)

Example​

// Convert to array
 const ts = new TreeSet<number>([3, 1, 2]);
      console.log(ts.toArray()); // [1, 2, 3];

values()​

values(): IterableIterator<K>;

Defined in: data-structures/binary-tree/tree-set.ts:1317

Iterate over values in ascending order.

Note: for Set-like containers, values() is the same as keys().

Returns​

IterableIterator<K>

Example​

// Get values (same as keys for Set)
 const ts = new TreeSet<number>([2, 1, 3]);
      console.log([...ts.values()]); // [1, 2, 3];

createDefaultComparator()​

static createDefaultComparator<K>(): Comparator<K>;

Defined in: data-structures/binary-tree/tree-set.ts:71

Create the strict default comparator.

Supports:

  • number (rejects NaN; treats -0 and 0 as equal)
  • string
  • Date (orders by getTime(), rejects invalid dates)

For other key types, a custom comparator must be provided.

Type Parameters​

K​

K

Returns​

Comparator<K>