JavaScript: Find a pair of elements from an specified array whose sum equals a specific target number

JavaScript Array: Exercise-26 with Solution

Find Pair with Target Sum

Write a JavaScript program to find a pair of elements (indices of the two numbers) in a given array whose sum equals a specific target number.

Input: numbers= [10,20,10,40,50,60,70], target=50
Output: 2, 3

Visual Presentation:

Sample Solution:

JavaScript Code:

// Function to find two indices in the array 'nums' whose elements sum to the 'target_num'
function twoSum(nums, target_num) {
 // Initialize an empty array 'map' to store the difference between 'target_num' and elements in 'nums'
 var map = [];
 // Initialize an empty array 'indexnum' to store the indices of the two numbers
 var indexnum = [];
 
 // Iterate through each element in the 'nums' array
 for (var x = 0; x < nums.length; x++) { // Check if the current element's complement exists in the 'map' array if (map[nums[x]] != null) { // If found, store the indices of the two numbers and break out of the loop var index = map[nums[x]]; indexnum[0] = index; indexnum[1] = x; break; } else { // If not found, store the index of the current element's complement in the 'map' array map[target_num - nums[x]] = x; } } // Return the array containing the indices of the two numbers return indexnum; } // Output the result of the twoSum function with a sample array and target number console.log(twoSum([10,20,10,40,50,60,70], 50)); 

Output:

[2,3]

Flowchart:

ES6 Version:

// Function to find two indices in the array 'nums' whose elements sum to the 'target_num'
const twoSum = (nums, target_num) => {
 // Initialize an empty array 'map' to store the difference between 'target_num' and elements in 'nums'
 const map = [];
 // Initialize an empty array 'indexnum' to store the indices of the two numbers
 const indexnum = [];
 // Iterate through each element in the 'nums' array
 for (let x = 0; x < nums.length; x++) { // Check if the current element's complement exists in the 'map' array if (map[nums[x]] != null) { // If found, store the indices of the two numbers and break out of the loop const index = map[nums[x]]; indexnum[0] = index; indexnum[1] = x; break; } else { // If not found, store the index of the current element's complement in the 'map' array map[target_num - nums[x]] = x; } } // Return the array containing the indices of the two numbers return indexnum; }; // Output the result of the twoSum function with a sample array and target number console.log(twoSum([10, 20, 10, 40, 50, 60, 70], 50)); 

Live Demo:

See the Pen JavaScript - Find a pair of elements from an specified array whose sum equals a specific target number - array-ex- 26 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that finds a pair of indices in an array whose corresponding values sum to a target using a hash map.
• Write a JavaScript function that iterates over an array and returns the first pair of indices that meet the target sum condition.
• Write a JavaScript function that sorts the array and employs a two-pointer technique to find the target sum pair.
• Write a JavaScript function that handles duplicate elements and returns all unique index pairs whose sum equals the target.

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