createHelloWorld. It should return a new function that always returns "Hello World".
Example 1:
Input: args = [] Output: "Hello World" Explanation: const f = createHelloWorld(); f(); // "Hello World" The function returned by createHelloWorld should always return "Hello World".
Example 2:
Input: args = [{},null,42]
Output: "Hello World"
Explanation:
const f = createHelloWorld();
f({}, null, 42); // "Hello World"
Any arguments could be passed to the function but it should still always return "Hello World".
Constraints:
0 <= args.length <= 10The key idea behind #2667 Create Hello World Function is understanding higher-order functions and how functions can return other functions. The task is to implement a function that returns another function which, when executed, always returns the string "Hello World".
The outer function acts as a factory that creates a new function. The returned function ignores any parameters passed to it and simply returns the constant string. This demonstrates a basic concept of closures and function composition, where a function can encapsulate behavior and return it for later execution.
Since the returned function performs a constant operation—returning a fixed string—no iteration or additional data structures are required. The implementation is straightforward and focuses mainly on correctly returning a function rather than executing it immediately.
Because the operation is constant, both time complexity and space complexity remain minimal.
| Approach | Time Complexity | Space Complexity |
|---|---|---|
| Return a constant function (Higher-Order Function) | O(1) | O(1) |
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This approach uses the concept of closures to return a function that ignores its arguments and always returns the string 'Hello World'. In this method, createHelloWorld returns a new function that consistently returns the string when invoked.
Time Complexity: O(1) as the function performs a constant-time operation.
Space Complexity: O(1) since it doesn't use any extra space dependent on input size.
1#include <stdio.h>
2
3const char* createHelloWorld() {
4 return "Hello World";
5}
6
7
In C, we use a function createHelloWorld that simply returns the string "Hello World". We then define a function pointer type hello_function to point to such functions and return it through another function getHelloWorldFunction.
This approach directly returns a function without using intermediate variables like closures. The returned function will always output 'Hello World', ignoring any provided arguments.
Time Complexity: O(1). The function executes a single return instruction.
Space Complexity: O(1) as there are no dynamic allocations.
1#include <functional>
2#include <string>
std::string helloWorldFunction() {
return "Hello World";
}
std::function<std::string()> createHelloWorld() {
return helloWorldFunction;
}Watch expert explanations and walkthroughs
Jot down your thoughts, approach, and key learnings
While this exact problem may not appear frequently in FAANG interviews, the concepts behind it—such as higher-order functions and closures—are very important in JavaScript and functional programming interviews.
No specific data structure is required for this problem. The task focuses on understanding functions and closures rather than storing or manipulating data.
The optimal approach is to return a function that always returns the string "Hello World". This demonstrates the concept of higher-order functions where a function can return another function for later execution.
The problem is designed to test understanding of higher-order functions and closures. Returning a function allows deferred execution, meaning the returned function can be called later to produce the result.
In C++, a direct function helloWorldFunction is created to return "Hello World" and returned as a std::function in createHelloWorld.