Algorithm for File Naming

Question

Algorithm for File Naming

Given an array of desired file names in the order of their creation, where two files cannot have the same name. If a file has a duplicate name, it will be appended with (k), where k is the smallest positive integer that creates a unique name.

Output an array of names for the files.

Example:

For names = ["doc", "doc", "image", "doc(1)", "doc"], the result should be fileNaming(names) = ["doc", "doc(1)", "image", "doc(1)(1)", "doc(2)"].

A solution provided by a user:

const fileNaming = names => {
    const used = {};
    return names.map(name => {
        let newName = name;
        while (used[newName]) {
            newName = `${name}(${used[name]++})`;
        }
        used[newName] = 1;
        return newName;
    });
};

There seems to be confusion regarding the condition in the while block.

The used object is initially empty.

The variable newName is set to the current item in the array.

How does used[newName] return a number if used is always an empty object?

Here is the console output for console.log(used[newName]):

https://i.sstatic.net/nCvwm.png

Using this input:

["dd", "dd(1)", "dd(2)", "dd", "dd(1)", "dd(1)(2)", "dd(1)(1)", "dd", "dd(1)"]

javascript

Answer 1

Answer №1

Within the realm of JavaScript, an empty object is symbolized by {} - this allows for an indefinite number of key-value pairs to be contained within it. If a key within this object is not defined, its corresponding value will be undefined, which in turn results in a false evaluation when tested. Nevertheless, any numerical value that is not zero or NaN will be evaluated as true:

console.log({}["a key that does not exist"])                 // undefined
while (undefined) {
    console.log("this should never be printed");             // never executes
}
while ({}["a key that does not exist"]) {
    console.log("this should never be printed");             // never executes
}
if (1) {
    console.log("positive numbers are true");                // writes to console
}

Objects can be used as maps, although the more modern approach involves utilizing actual maps instead in contemporary code.

A more concise rendition of the aforementioned program would have been:

return names.map(name => {
    let newName = name;
    while (used[newName] !== undefined) {       // tests for "not undefined"
        newName = `${name}(${used[name]})`;     // utilizes current value
        used[name] = used[name] + 1;            // establishes a larger value            
    }
    used[newName] = 1;                          // assigns a value
    return newName;
});

Answer 2

Within the realm of JavaScript, an empty object is symbolized by {} - this allows for an indefinite number of key-value pairs to be contained within it. If a key within this object is not defined, its corresponding value will be undefined, which in turn results in a false evaluation when tested. Nevertheless, any numerical value that is not zero or NaN will be evaluated as true:

console.log({}["a key that does not exist"])                 // undefined
while (undefined) {
    console.log("this should never be printed");             // never executes
}
while ({}["a key that does not exist"]) {
    console.log("this should never be printed");             // never executes
}
if (1) {
    console.log("positive numbers are true");                // writes to console
}

Objects can be used as maps, although the more modern approach involves utilizing actual maps instead in contemporary code.

A more concise rendition of the aforementioned program would have been:

return names.map(name => {
    let newName = name;
    while (used[newName] !== undefined) {       // tests for "not undefined"
        newName = `${name}(${used[name]})`;     // utilizes current value
        used[name] = used[name] + 1;            // establishes a larger value            
    }
    used[newName] = 1;                          // assigns a value
    return newName;
});

Algorithm for File Naming

Answer №1

Similar questions

Retrieving the result of a callback function within a nested function

What is the reason behind the execution of componentDidMount occurring after componentWillUnmount?

The Heroku Node.js application encountered an issue when trying to apply the style due to an incompatible MIME

Enter key always causes the Bootstrap form to submit

"Utilize Ajax to dynamically generate options in a dropdown menu with multiple

Any ideas for handling ProtractorJS timeouts while clicking an element?

Tips for gathering an array of checkboxes within a dynamic array of items using Vue.js and Vuetify

Getting the values of several labels using a class name - a comprehensive guide

Guidance on using an array to filter an object in Javascript

Using the "this" keyword in JavaScript to access the "rel"

Strategies to manage or prevent a timezone offset while deploying a Next.js application on Vercel

Embed a function within a string literal and pass it to another component

The barcode is not displaying when using javascript:window.print() to print

Tips for utilizing Sass and CSS Modules within create-react-app

Understanding which page is being rendered through _app.js in React/Next.js is crucial for seamless navigation and

A comprehensive guide to using Reactive Forms in Angular

Using Electron to Show a Video Stored in the Local File System Using a Custom Protocol

Is there a way to directly access the React component that was clicked?

Encountering an 'Undefined' error when trying to access data object values within the map function in a

The filter function in JavaScript's Array is malfunctioning on Internet Explorer version 7