Two Sum

My Solution

Python

def twoSum(nums: List[int], target: int) -> List[int]:
    for i in range(len(nums)):
      y = target - nums[i]
      sublist = nums[i+1:]
      if y in sublist:
          return [i, nums.index(y, i+1)]

def twoSum(nums: List[int], target: int) -> List[int]:
    hash_map = {}

    for i in range(len(nums)):
        y = target - nums[i]
        if y in hash_map:
            return [i, hash_map[y]]

        hash_map[nums[i]] = i

Brute Force: O(n^2)

def twoSum(nums: List[int], target: int) -> List[int]:
    for i in range(len(nums) - 1):
        for num in nums[i+1:]:
            if nums[i] + num == target:
                return [i, nums[i+1:].index(num) + i + 1]

JavaScript

(TypeScript, technically)

function twoSum(nums: number[], target: number): number[] {
  const hashTable = {};

  for (let i = 0; i < nums.length; i++) {
    let diff = target - nums[i];
    if (diff in hashTable) {
      return [hashTable[diff], i];
    } else {
      hashTable[nums[i]] = i;
    }
  }
}