What is the Two Sum problem?

What is the Two Sum problem?

The Two Sum problem is a classic algorithmic challenge where you need to find two numbers in an array that add up to a specific target.

Can you give me an example?

Sure! If you have an array [2, 7, 11, 15] and a target of 9, the numbers 2 and 7 add up to 9.

How would you solve it in Python?

You can use a dictionary to store the numbers and their indices. Here's a simple solution:

def two_sum(nums, target):
    num_map = {}
    for i, num in enumerate(nums):
        complement = target - num
        if complement in num_map:
            return [num_map[complement], i]
        num_map[num] = i

What is the time complexity of this solution?

The time complexity of this solution is O(n), where n is the number of elements in the array, because we traverse the list once.