CODE EXAMPLE FOR JAVASCRIPT

two sum js

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
	// return brute(nums,target);
    return memoization(nums, target);
};

// Naive Approach: Brute Force | O(N^2) | O(1)
const brute = (nums, target) => {
  for (let i = 0; i < nums.length - 1; i++) {
    for (let j = i+1; j < nums.length; j++) {
      if (nums[i]+nums[j] === target) return [i,j];
    }
  }
  return []
};

// Memoization: HashMap | O(N) | O(N)
const memoization = (nums, target) => {
  const memo = {}; 
  for (let i = 0; i < nums.length; i++) {
    if (Number.isInteger(memo[nums[i]])) return [memo[nums[i]], i];
    else memo[target - nums[i]] = i;
  }
  return []; 
};