K-Means Clustering

K-means finds groups in unlabeled data. Starting from the given centroids, repeat iterations times:

Assign: put each point in the cluster of its nearest centroid (Euclidean distance). If two centroids are equally close, choose the one with the smaller index.
Update: move each centroid to the average of the points assigned to it. A centroid with no points stays where it is.

Implement k_means(points, centroids, iterations).

Input

points: The data points, each a list of coordinates.

centroids: The k starting centroids, with the same number of coordinates.

iterations: How many assign-and-update rounds to run.

Output

Return the final centroids in their original order.

Constraints

1 ≤ number of points ≤ 1,000, 1 ≤ k ≤ 20, 1 ≤ dimensions ≤ 10

0 ≤ iterations ≤ 100

-1,000 ≤ each coordinate ≤ 1,000

Examples

Example 1

Input:
points = [
    [1.0, 1.0],
    [1.5, 2.0],
    [8.0, 8.0],
    [9.0, 8.5]
]
centroids = [
    [0.0, 0.0],
    [10.0, 10.0]
]
iterations = 1

Expected output:
[
    [1.25, 1.5],
    [8.5, 8.25]
]

Explanation

The first two points are nearer to (0, 0) and the last two nearer to (10, 10). The new centroids are the averages: ((1 + 1.5) / 2, (1 + 2) / 2) = (1.25, 1.5) and ((8 + 9) / 2, (8 + 8.5) / 2) = (8.5, 8.25).

Example 2

Input:
points = [
    [0.0],
    [1.0],
    [10.0]
]
centroids = [
    [0.0],
    [100.0]
]
iterations = 2

Expected output:
[
    [3.666667],
    [100.0]
]

Explanation

Round 1: (100) is far from every point, so all three points join centroid 1, which moves to (0 + 1 + 10) / 3 ≈ 3.666667; centroid 2 gets no points and stays at 100. Round 2 assigns the same way, so the result is [[3.666667], [100]].

References

scikit-learn, K-means clustering

Run the sample tests to check your code without submitting.

Example 1 Not run

Input:

points = [
    [1.0, 1.0],
    [1.5, 2.0],
    [8.0, 8.0],
    [9.0, 8.5]
]
centroids = [
    [0.0, 0.0],
    [10.0, 10.0]
]
iterations = 1

Expected output:

[
    [1.25, 1.5],
    [8.5, 8.25]
]

Your output

Example 2 Not run

Input:

points = [
    [0.0],
    [1.0],
    [10.0]
]
centroids = [
    [0.0],
    [100.0]
]
iterations = 2

Expected output:

[
    [3.666667],
    [100.0]
]

Your output

4 hidden tests also run when you submit. If your code fails one, you'll see that test. Solve the challenge to see them all.

Online Go Compiler

Write, compile, run, and debug Go code online in a full-featured browser IDE. Work with multiple files, save your workspace, and collaborate in real time - no setup required.

Version

Pre-installed Libs

🚀 206,970 total executions (799 this month)

Output

Practice Go with coding challenges

Solve hands-on problems right in this editor: run the sample tests, submit, and get an AI code review.

All Go challenges

Easy

Rectangle Perimeter

Compute the perimeter of a rectangle from its sides.

You'll learn ArithmeticReturn values

BeginnerLearning-pathVariables

View solutions (12)

Easy

Distance Between Points

Compute the straight-line distance between two points.

You'll learn Pythagorean theoremSquare roots

BeginnerFunctionsLearning-pathmath

View solutions (7)

Easy

Days in a Month

Return how many days a month has, including leap years.

You'll learn Calendar rulesHelper functions

BeginnerConditionsFunctionsLearning-path

View solutions (6)

Easy

Average of Three

Average three whole numbers.

You'll learn ArithmeticDivision

BeginnerLearning-pathVariables

View solutions (6)

Easy

Dot Product of Two Vectors

Multiply two vectors element by element and add the results: the core operation of every neuron.

You'll learn VectorsDot product

Neural networksaimachine learning

View solutions (4)

Easy

Largest of Three

Pick the largest of three numbers without a built-in max.

You'll learn ComparisonsCombining conditions

BeginnerConditionsLearning-path

View solutions (4)

Easy

Prime Number Check

Decide whether a number is prime.

You'll learn DivisibilityLoop optimization

BeginnerLoopsNumbersStudent-beginner

View solutions (3)

Easy

Number Triangle

Build a triangle of increasing numbers.

You'll learn Growing rowsCounters across rows

BeginnerLearning-pathNested-loopsPatterns

View solutions (3)

Easy

Armstrong Number

Check whether a number equals the sum of its digits raised to the digit count.

You'll learn Digit extractionPowers

BeginnerNumbersStudent-beginner

View solutions (3)

Easy

Row Sums

Add up every row of a grid.

You'll learn 2D listsNested loops

BeginnerGridsLearning-path

View solutions (3)

Easy

Min and Max Together

Find the smallest and largest value in one pass.

You'll learn Single passMultiple return values

ArraysBeginnerFunctionsLearning-path

View solutions (3)

Easy

Count Pairs With a Sum

Count pairs of positions whose values add up to a target.

You'll learn Pairs of indexesAvoiding double counts

ArraysBeginnerLearning-pathNested-loops

View solutions (3)

🐹 About This Go Online Executor

The CodeUtility Go Executor lets you write and run Go code directly in your browser - no installation, setup, or local environment required. It’s powered by a secure sandbox that supports real Go compiler versions 1.19, 1.20, and 1.21.

This tool compiles and executes real Go programs in the cloud, giving you an authentic Go environment. You can test short snippets, experiment with packages, and explore Go’s powerful concurrency features using goroutines and channels.

It’s perfect for learning and practicing core Go concepts such as variables, functions, structs, slices, maps, interfaces, and error handling - all without installing any tools locally.

Whether you’re exploring Go for the first time, testing backend logic, or learning how concurrency works, the CodeUtility Go Executor offers a clean, fast, and browser-based way to run Go code instantly.

More than a code runner

Use a multi-file editor, an isolated execution terminal, runtime-specific libraries, persistent workspaces, sharing, and real-time collaboration from the same executor.

How to use this executor?

Choose a runtime, open or create a file, write your code, and select Run. Output appears in the terminal, while signed-in users can keep files in a workspace, install libraries, and collaborate through shares.

Select a version and edit the current file or open another workspace file.
Run the code, provide input in the terminal when requested, and review saved run history.
Use libraries, workspace tools, sharing, and chat when your task needs more than one snippet.

Start coding

VersionSelect a runtime before running. Installed libraries belong to the selected language version.
Open files lists unopened text files. Select one to open it in an available editor tab.
Run executes the active file with its workspace available to the program.
Stop ends the current execution before its time limit.
Advanced Mode opens the IDE layout with a file explorer and movable, resizable terminal.

Workspace and libraries

New file creates a file in the selected parent directory and opens it in the editor.
New folder creates a directory, up to the supported nesting depth.
Upload files adds one or more safe files to a directory.
Download saves a file or a zipped directory to your device.
Copy duplicates a workspace file or directory.
Rename changes a file name and updates its open tab and history.
Move relocates an item; files and directories can also be dragged.
Delete removes an item after confirmation and closes its open editor tab.
Pre-installed Libs shows packages already included in this runtime.
Add Lib installs a private package for your account and selected runtime.

Terminal and assistance

Run history opens previous and next saved outputs.
Copy output copies the current terminal text.
Clear output removes all saved run outputs after confirmation.
Explain summarizes the active code.
Recents opens recent explanations and results.
Settings changes fonts, themes, and visible toolbar buttons.

Sharing and collaboration

Share publishes the current file, a directory, or the whole workspace as a snapshot or live workspace. You control link access and who may save changes.
Logs records saved collaborator actions in a shared workspace.
Share chat lets signed-in participants message, mention people, share code blocks, and see online or typing members.
Live collaboration shows collaborator cursors and saved file updates. View-only users can load the latest version or keep temporary edits.

Quotas and limits

Execution time is limited to 20 seconds per server run. Use Stop when you want to end it sooner.
Workspace storage allows 100 files, 100 directories, and 10 MiB total for each signed-in user workspace and language.
Files and folders are limited to 1 MiB per file and 5 nested directory levels. Files generated by your code follow the same quota.
Private libraries are limited to 10 installed packages for each account and runtime.
Share snapshots can contain up to 100 files, 1 MiB per file, and 2 MiB total.
Share invitations support up to 25 people per share, with access and saving permissions managed separately.
Share chat allows 2,000 characters per message and 10,000 messages per share.
Quota enforcement also applies while code is running. A write that exceeds file count, size, storage, or nesting limits is rejected safely.

Good to know Only run code and install packages you trust. Execution is isolated and limited, but your program can still modify files inside a writable workspace up to its enforced quota.

💡 Go Basics & Examples You Can Try Above

1. Declaring Variables and Constants

Use var or := to declare variables. Use const for constants.

package main

var x int = 10
const Pi = 3.14

func main() {
    name := "Alice"
    isActive := true
    println(x, Pi, name, isActive)
}

2. Conditionals (if / switch)

Go supports if-else and switch statements with clean syntax.

x := 2
if x == 1 {
    println("One")
} else if x == 2 {
    println("Two")
} else {
    println("Other")
}

switch x {
case 1:
    println("One")
case 2:
    println("Two")
default:
    println("Other")
}

3. Loops

Go uses only the for loop, but it can act like a while loop.

for i := 0; i < 3; i++ {
    println(i)
}

n := 3
for n > 0 {
    println(n)
    n--
}

4. Arrays

Arrays have fixed size. Use slices for dynamic lists.

var nums = [3]int{10, 20, 30}
println(nums[1])

5. Slice Manipulation

Use slices and the built-in append, len, copy, and slicing syntax.

fruits := []string{"apple", "banana"}
fruits = append(fruits, "cherry")
fruits = fruits[1:]  // slice
println(len(fruits))

for _, fruit := range fruits {
    println(fruit)
}

6. Console Input/Output

Use fmt.Print, fmt.Scan, and fmt.Println.

import "fmt"

var name string
fmt.Print("Enter your name: ")
fmt.Scan(&name)
fmt.Println("Hello", name)

7. Functions

Functions are declared with func and can return multiple values.

func greet(name string) string {
    return "Hello, " + name
}

message := greet("Alice")
println(message)

8. Maps

Maps are key-value stores. Declare with make().

ages := map[string]int{"Alice": 30}
ages["Bob"] = 25
println(ages["Alice"])

9. Error Handling

Go uses multiple return values for errors instead of exceptions.

import "errors"

func fail() error {
    return errors.New("something went wrong")
}

err := fail()
if err != nil {
    println(err.Error())
}

10. File I/O

Use os and io/ioutil packages to read/write files.

import (
  "fmt"
  "os"
  "io/ioutil"
)

ioutil.WriteFile("file.txt", []byte("Hello File"), 0644)

data, _ := ioutil.ReadFile("file.txt")
fmt.Println(string(data))

11. String Manipulation

Use the strings package for string operations.

import "strings"

text := "  Hello World  "
println(strings.TrimSpace(text))
println(strings.ToUpper(text))
println(strings.ReplaceAll(text, "Hello", "Hi"))

words := strings.Split(text, " ")
fmt.Println(words)

12. Structs & Objects

Use structs to define custom types with methods.

type Person struct {
  Name string
}

func (p Person) Greet() string {
  return "Hi, I'm " + p.Name
}

p := Person{Name: "Alice"}
println(p.Greet())

13. References (Pointers)

Go supports pointers using * and &.

x := 10
ptr := &x
*ptr = 20
println(x) // 20