Problem Description
In the town of Digitville, there was a list of numbers called nums containing integers from 0 to n - 1. Each number was supposed to appear exactly once in the list, however, two mischievous numbers sneaked in an additional time, making the list longer than usual. Your task is to find these two sneaky numbers. Return an array of size two containing the two numbers (in any order), so peace can return to Digitville.
Key Insights
- The length of the input array is n + 2, meaning there are two duplicate numbers.
- The numbers in the array range from 0 to n - 1.
- A counting approach or a hash set can be utilized to identify the duplicate numbers efficiently.
Space and Time Complexity
Time Complexity: O(n)
Space Complexity: O(n)
Solution
To identify the two sneaky numbers, we can use a hash set to keep track of the numbers we've seen as we iterate through the array. As we go through each number, we check if it's already in the set. If it is, then it's one of the duplicates we are looking for. If it's not, we add it to the set. We continue this process until we've found both duplicate numbers.