JavaScript: Find a pair of elements from an specified array whose sum equals a specific target number
JavaScript Array: Exercise-26 with Solution
Write a JavaScript program to find a pair of elements (indices of the two numbers) from an given array whose sum equals a specific target number.
Input: numbers= [10,20,10,40,50,60,70], target=50
Output: 2, 3
Pictorial Presentation:
Sample Solution:
HTML Code:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Find a pair of elements from an specified array whose sum equals a specific target number</title>
</head>
<body>
</body>
</html>
JavaScript Code:
function twoSum(nums, target_num) {
var map = [];
var indexnum = [];
for (var x = 0; x < nums.length; x++)
{
if (map[nums[x]] != null)
{
var index = map[nums[x]];
indexnum[0] = index;
indexnum[1] = x;
break;
}
else
{
map[target_num - nums[x]] = x;
}
}
return indexnum;
}
console.log(twoSum([10,20,10,40,50,60,70],50));
Sample Output:
[2,3]
Flowchart:
ES6 Version:
function twoSum(nums, target_num) {
const map = [];
const indexnum = [];
for (let x = 0; x < nums.length; x++)
{
if (map[nums[x]] != null)
{
var index = map[nums[x]];
indexnum[0] = index;
indexnum[1] = x;
break;
}
else
{
map[target_num - nums[x]] = x;
}
}
return indexnum;
}
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.
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Next: Write a JavaScript function to retrieve the value of a given property from all elements in an array.
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JavaScript: Tips of the Day
How to insert an item into an array at a specific index (JavaScript)?
What you want is the splice function on the native array object.
arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:
var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());
Ref: https://bit.ly/2BXbp04
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