Two Sum

Problem #two-sumEasy

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

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

You can return the answer in any order.

Examples:

Input: nums = [2,7,11,15], target = 9

Output: [0,1]

Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Input: nums = [3,2,4], target = 6

Output: [1,2]

Explanation: Because nums[1] + nums[2] == 6, we return [1, 2].

Input: nums = [3,3], target = 6

Output: [0,1]

Explanation: Because nums[0] + nums[1] == 6, we return [0, 1].

Constraints:

2 <= nums.length <= 10^4
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Only one valid answer exists.

Hints:

Try using a HashMap to store values you've seen.
For each number, check if target - number exists in the HashMap.
Using a single pass approach, you can solve this in O(n) time complexity.

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        # Your code here
        passclass Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        # Your code here
        pass