Finding the difference or sum within an array to identify the two numbers that produce a new array

Question

Finding the difference or sum within an array to identify the two numbers that produce a new array

In order to clarify, I am looking for a method to identify the two smallest numbers in a sorted array that will result in a specific number when subtracted. The process can be broken down into the following steps:

Iterate through the array and designate a current value from which other numbers will be subtracted.

Continue this process until you find the numbers that match the desired result, then return them.

For example, let's say we are looking for two numbers that, when subtracted from the array, result in 2.
Let givenArray = [1, 4, 8, 10];
The subtraction would proceed as follows: 4 - 1 = 3 (no match); // continue
                                           8 - 4 = 4 (no match); // continue
                                           8 - 1 = 7 (no match); // continue
                                           10 - 8 = 2 (match found); // stop and return 8, 10.

NOTE: It is possible that the same array may contain both 6 and 8 or 8 and 10, either of which results in 2. However, if both are present, 6 and 8 should be returned. The exact method used to generate the array is not crucial.

P.S: I was able to solve this issue yesterday, but I welcome any additional suggestions on how to approach it.

javascript arrays

Answer 1

Answer №1

This clever solution harnesses the power of a hash table and employs a single-loop strategy to extract two values from an array in order to achieve balance.

To begin, calculate the absolute difference between the two values in arrayA and use this information to extract the values from the larger array.

Next, iterate through the larger array arrayB while checking for the presence of the required value and ensuring that the sum is smaller than any previously identified set.

The criteria for validation are based on the absolute difference between delta and v, where v represents the current array value, or by evaluating the sum of delta and v.

Lastly, to ensure the functionality of the process, the current value v is added to the hash table for future reference.

The outcome will be either an array containing two values that balance the original pair or undefined if no suitable values are found.

var arrayA = [3, 5],
    arrayB = [2, 9, 5, 4],
    delta = Math.abs(arrayA[0] - arrayA[1]),
    values = {},
    result = arrayB.reduce((r, v) => {
        function check(w) {
            if (!values[w] || r && r[0] + r[1] < v + w) return;
            r = [w, v];
        }
        check(Math.abs(delta - v));
        check(delta + v);
        values[v] = true;
        return r;
    }, undefined);

console.log(result);

Answer 2

This clever solution harnesses the power of a hash table and employs a single-loop strategy to extract two values from an array in order to achieve balance.

To begin, calculate the absolute difference between the two values in arrayA and use this information to extract the values from the larger array.

Next, iterate through the larger array arrayB while checking for the presence of the required value and ensuring that the sum is smaller than any previously identified set.

The criteria for validation are based on the absolute difference between delta and v, where v represents the current array value, or by evaluating the sum of delta and v.

Lastly, to ensure the functionality of the process, the current value v is added to the hash table for future reference.

The outcome will be either an array containing two values that balance the original pair or undefined if no suitable values are found.

var arrayA = [3, 5],
    arrayB = [2, 9, 5, 4],
    delta = Math.abs(arrayA[0] - arrayA[1]),
    values = {},
    result = arrayB.reduce((r, v) => {
        function check(w) {
            if (!values[w] || r && r[0] + r[1] < v + w) return;
            r = [w, v];
        }
        check(Math.abs(delta - v));
        check(delta + v);
        values[v] = true;
        return r;
    }, undefined);

console.log(result);

Answer 3

Answer №2

It seems like there may be some confusion, but here is a potential solution for your issue:

const difference = arrayA[1] - arrayA[0];

let index1, index2;
for (index1 = arrayB.length - 1; index1 >= 1; index1--) { // Set the first value
    for (index2 = arrayB.length - 1; index2 >= 1; index2--) { // Set the second value
        if (index1 !== index2) {
            if (
                arrayB[index1] - arrayB[index2] === difference // Check subtraction
                || arrayB[index1] + arrayB[index2] === difference // Check addition
            ) return [arrayB[index1], arrayB[index2]];
        }
    }
}

Answer 4

It seems like there may be some confusion, but here is a potential solution for your issue:

const difference = arrayA[1] - arrayA[0];

let index1, index2;
for (index1 = arrayB.length - 1; index1 >= 1; index1--) { // Set the first value
    for (index2 = arrayB.length - 1; index2 >= 1; index2--) { // Set the second value
        if (index1 !== index2) {
            if (
                arrayB[index1] - arrayB[index2] === difference // Check subtraction
                || arrayB[index1] + arrayB[index2] === difference // Check addition
            ) return [arrayB[index1], arrayB[index2]];
        }
    }
}

Finding the difference or sum within an array to identify the two numbers that produce a new array

Answer №1

Answer №2

Similar questions

Ways to get a Discord bot to echo a message?

Appending a JSON object to an array does not result in the object being added to the

What is the best way to retrieve the directory path from a FileReader in Java

Tips on creating a slow and gradual border animation that unfolds smoothly

What is the process for retrieving an Object from $cookies?

Is there a way to obtain the current URL within the index.html file using Vue.js?

attempting to fulfil a promise through a resolution

The JQuery parseFloat() function seems to be consistently returning "NAN" whenever it is used with the .text property

What is the most effective method to retrieve the UserName using Javascript?

Tips for clearing a material-ui search input field with the help of a button

What is the process for retrieving the value of `submit.preloader_id = "div#some-id";` within the `beforesend` function of an ajax call?

There seems to be a connection issue between my Jquery and HTML, as they

What is the best way to interact with my component in React?

Secure an input field for exclusive attention. React

Incorporate ng-model to manage dynamically generated HTML elements

Using jQuery Datepicker, showcase two distinct datepickers on a single page

I am experiencing issues with the middleware not functioning properly after implementing a custom application with Next.js

What is the process for executing PhantomJS commands through a NodeJs server?

Attempting to execute npm install for an Odin project task, encountered the error "Module not Found". // A new error has surfaced, continue reading below

In JavaScript, promises remain in a pending state