LeetCode 2703 - Return Length of Arguments Passed

LeetCode Problem 2703

Difficulty: 🟢 Easy
Topics: —

Solution

Problem Understanding

The problem asks for a function that returns the number of arguments passed to it. Essentially, we need to measure the length of the input in a dynamic, variadic sense. The input is presented as a JSON array in the examples, representing all the arguments passed to the function. The expected output is an integer representing how many distinct values were given as input.

Constraints are minimal: the array length can range from 0 to 100, and all elements are valid JSON values. This indicates that performance concerns are trivial, and we only need to ensure correctness for empty arrays, single-element arrays, and arrays containing various types (numbers, strings, objects, null). Important edge cases include calling the function with no arguments, or arguments that are falsy like 0, "", or null, which should still be counted.

Approaches

The most straightforward approach is to leverage the native ability of programming languages to capture variadic arguments. In Python, we can use *args to collect any number of positional arguments into a tuple. In Go, we can use a variadic function with ...interface{} to collect all arguments. Once the arguments are collected, the solution reduces to returning the length of the collection.

A brute-force approach is unnecessary in this context because variadic parameters already provide the complete list. There are no complex calculations or iterations required beyond measuring the length.

Approach	Time Complexity	Space Complexity	Notes
Brute Force	O(n)	O(n)	Iterate manually over arguments array and count them
Optimal	O(1)	O(1)	Use language feature to capture all arguments and return length

The optimal approach is essentially constant time because measuring the length of a collected argument list is done in O(1) time in Python and Go for small numbers of arguments (up to 100, as constrained).

Algorithm Walkthrough

1. Define a function argumentsLength that accepts a variadic number of arguments.
2. Collect all passed arguments into a list or tuple (Python) or a slice (Go) using variadic syntax.
3. Measure the length of the collected arguments using the native length operator.
4. Return this integer as the result.

Why it works: By capturing all input arguments, we guarantee that no argument is missed, including falsy or null values. Counting the length of this collection accurately returns the total number of arguments passed.

Python Solution

def argumentsLength(*args) -> int:
    return len(args)

This Python implementation uses the *args syntax to collect all positional arguments into a tuple named args. The len function then returns the number of elements in this tuple, which is exactly the number of arguments passed to the function. The implementation is concise, direct, and handles all edge cases automatically.

Go Solution

func argumentsLength(args ...interface{}) int {
    return len(args)
}

In Go, the ...interface{} syntax allows the function to accept any number of arguments of any type. These arguments are collected into a slice named args. The built-in len function returns the length of this slice, which corresponds to the number of arguments provided. This implementation mirrors the simplicity of the Python solution.

Worked Examples

For input [5], the arguments are captured as a single-element tuple or slice. len(args) returns 1.

For input [{}, null, "3"], the arguments are captured as a three-element collection. len(args) returns 3.

For input [] (no arguments), the captured collection is empty, and len(args) returns 0.

Input	Collected Args	Result
[5]	(5,) or []interface{}{5}	1
[{}, null, "3"]	({}, None, "3") or []interface{}{map[string]interface{}{}, nil, "3"}	3
[]	() or []interface{}{}	0

Complexity Analysis

Measure	Complexity	Explanation
Time	O(1)	Counting the length of the collected arguments is constant time for up to 100 elements.
Space	O(n)	The function stores all arguments in a tuple or slice; n is the number of arguments passed.

Even though time complexity is effectively O(1) for small n, space complexity scales linearly with the number of arguments because each argument is stored in a collection.

Test Cases

# Basic test cases
assert argumentsLength(5) == 1  # single argument
assert argumentsLength({}, None, "3") == 3  # multiple types
assert argumentsLength() == 0  # no arguments

# Edge cases
assert argumentsLength(0, "", False, None) == 4  # falsy values still counted
assert argumentsLength(*range(100)) == 100  # maximum allowed number of arguments
assert argumentsLength("a", "b", "c") == 3  # string arguments

Test	Why
single argument	verifies minimal input works
multiple types	ensures all types are counted
no arguments	validates handling of empty input
falsy values	ensures falsy values are not skipped
maximum arguments	tests boundary condition of n = 100
string arguments	checks common usage with strings

Edge Cases

The first important edge case is when no arguments are passed. A naive implementation might attempt to access the first element and fail, but using variadic syntax ensures an empty collection is returned, which correctly results in 0.

The second edge case is when arguments include falsy values such as 0, "", False, or None. Some implementations might inadvertently ignore these, but capturing all arguments and measuring length counts them correctly.

The third edge case is the upper limit of 100 arguments. While performance is trivial for such a small number, this tests the function's ability to handle the maximum allowed size, ensuring no indexing errors or overflow occurs. Both Python and Go handle this seamlessly with their variadic collection mechanisms.