---
tags: data_structure_python
---

# Two Sum <img src="https://img.shields.io/badge/-easy-brightgreen">

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.

<ins>**Example**</ins>:

>Given nums = [2, 7, 11, 15], target = 9,
>
>Because nums[0] + nums[1] = 2 + 7 = 9,
>return [0, 1].

## Solution

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        bag = {}
        
        for i, elt in enumerate(nums):
            if elt in bag:
                return [i, bag[elt]]
            bag[target-elt] = i