Two Sum
Updated Jan 31, 2026
Problem
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.
Constraints
2 <= nums.length <= 10^4
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Exactly one valid answer exists.
Examples
Example 1
Input:
nums = [2, 7, 11, 15], target = 9
Output:
[0, 1]
Example 2
Input:
nums = [3, 2, 4], target = 6
Output:
[1, 2]
Example 3
Input:
nums = [3, 3], target = 6
Output:
[0, 1]
Function Signature
def twoSum(self, nums: list[int], target: int) -> list[int]
How to Submit
Implement a Solution class with a twoSum method.
Your method will be called with the input parameters and should return the answer.