Create Hello World Function - Practice Coding Problems

Create Hello World Function - Problem

JavaScript Easy

Write a function createHelloWorld. It should return a new function that always returns "Hello World".

This problem introduces the concept of closures in JavaScript - functions that have access to the outer (enclosing) scope's variables even after the outer function has returned.

Input & Output

Example 1 — Basic Function Creation

$ Input: createHelloWorld()

› Output: function that returns "Hello World"

💡 Note: createHelloWorld() returns a new function. When that returned function is called, it outputs "Hello World"

Example 2 — Multiple Calls

$ Input: const f = createHelloWorld(); f(); f();

› Output: "Hello World", "Hello World"

💡 Note: The same returned function can be called multiple times, always returning the same string

Example 3 — Multiple Instances

$ Input: const f1 = createHelloWorld(); const f2 = createHelloWorld();

› Output: Two independent functions, both return "Hello World"

💡 Note: Each call to createHelloWorld() creates a new function instance, but they all behave identically

Constraints

The returned function should always return the exact string "Hello World"
No parameters are passed to createHelloWorld or the returned function

Visualization

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Understanding the Visualization

Input

Call createHelloWorld() with no parameters

Process

Create and return inner function

Output

Returned function always outputs "Hello World"

Key Takeaway

🎯 Key Insight: Functions can return other functions, creating flexible and reusable code patterns

Asked in

G Google 15 f Facebook 12 a Amazon 8 M Microsoft 6

The key insight is understanding higher-order functions and closures. The createHelloWorld function should return another function that always returns "Hello World". Best approach is the direct function return for simplicity. Time: O(1), Space: O(1)

Common Approaches

Approach	Time	Space	Notes
✓ Closure with Message Storage	O(1)	O(1)	Use closure to store the message and return a function that accesses it
Direct Function Return	O(1)	O(1)	Return a simple function that always returns the string literal

Closure with Message Storage — Algorithm Steps

Step 1: Store message in outer function scope
Step 2: Return inner function that accesses stored message

Visualization

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Step-by-Step Walkthrough

Outer Scope

createHelloWorld stores message variable

Inner Function

Returned function captures message via closure

Access

Inner function can access captured message anytime

Code -

solution.c — C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
    char* message;
} Closure;

typedef char* (*HelloWorldFunc)(Closure*);

char* helloWorldWithClosure(Closure* closure) {
    return closure->message;
}

char* solution() {
    static Closure closure;
    static char message[] = "Hello World";
    closure.message = message;
    
    HelloWorldFunc createHelloWorld() {
        return helloWorldWithClosure;
    }
    
    HelloWorldFunc result = createHelloWorld();
    return result(&closure);
}

int main() {
    char* result = solution();
    printf("%s\n", result);
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(1)

Storing message and returning function takes constant time

✓ Linear Growth

Space Complexity

O(1)

Only stores one string in closure scope

✓ Linear Space

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Smart Actions

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Input & Output

Constraints

Visualization

Related Problems

Common Approaches

Closure with Message Storage — Algorithm Steps

Visualization

Code -

Time & Space Complexity

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