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

Unreachable prevState when utilizing the useState hook

Execute an AJAX call to remove a comment

AngularJS SmartyUI position not dynamically updating on SmartyStreets plugin

Oops, it seems like the project is missing a `pages` directory. Please kindly create one in the project root. Thank you!

Execute an AJAX post request to the identical PHP page (utilizing the Jquery Form Plugin)

I wonder where the file from the HTML form download has originated

Loading content from another webpage within a webpage using Ajax

using http to handle a 404 error

Child component destruction triggers an ongoing digestion process

How come I can never seem to make it past the number 1?

How can I use the select2 jQuery plugin with the tags:true option to ensure that selected choices do not appear again in the dropdown menu?

When an import is included, a Typescript self-executing function will fail to run

My Angular Router is creating duplicate instances of my route components

Is there a way for me to gain entry to this array in vuejs?

Issue: Module 'curl' is not located at Function.Module._resolveFilename (module.js:489:15)

Having trouble with installing Node Windows NPM?

Changing the structure of a JSON array in JavaScript

Vue Method always executed (regardless of click event)

Compatibility of HTML5 websites with Internet Explorer

How can I display the most recent offcanvas opening at the top of the page?