Two Sum

Find indices of two numbers in an array that add up to a target value using a hash map for O(n) time complexity.

Code

Algorithms

const map = new Map();
let result = null;
for (let i = 0; i < arr.length; i++) {
  const complement = target - arr[i];
  if (map.has(complement)) { result = [map.get(complement), i]; break; }
  map.set(arr[i], i);
}
return result;

Parameters

arr(array)

Array of numbers

target(number)

Target sum

Browser·fetch() may be limited by CORS

More JavaScript Snippets

Array Difference

Find elements in the first array that are not present in the second array.

Array Frequencies

Count how many times each value appears in an array and return a frequency map.

Array Head

Get the first n elements of an array.

Array Intersection

Find common elements that exist in both arrays.

Array Tail

Get the last n elements of an array.

Array Union

Combine two arrays and remove duplicates to produce a union.