 @tesla809/ Files
• index.js
index.js
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```
```/*
Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.
*/

const arr = [2, 7, 11, 15];

const twoSum = function(nums, target) {
// hash tables have O(1) running time.
// use instead of arrays with O(n) time.
// trade space over time.
const hashTable = {};
const resultSumsArr =[];
const length = nums.length;

// loop over array
for(let i = 0; i < length; i++) {
// subtract element from target
// since we are looking for two integers
// that add up to target, by subtracting
// one integer, we can get the other.
let integer1 = target - nums[i];

// if found in hash table, its it
// Aka the integer if the integer is found
// in the table, then we have our matching pair!
// this is more efficent than using double loop
// of O(n^2) time.
if (hashTable[integer1] !== undefined) {
resultSumsArr.push(nums[i], integer1);
}

// key is string representation of integer, value is integer.
hashTable[nums[i].toString()] = nums[i];
}
return resultSumsArr;
};

const answer = twoSum(arr, 9);