You have a set of integers s, which originally contains all the numbers from 1 to n. Unfortunately, due to some error, one of the numbers in s got duplicated to another number in the set, which results in repetition of one number and loss of another number.
You are given an integer array nums representing the data status of this set after the error.
Find the number that occurs twice and the number that is missing and return them in the form of an array.
Example 1:
Input: nums = [1,2,2,4] Output: [2,3]
Example 2:
Input: nums = [1,1] Output: [1,2]
Constraints:
2 <= nums.length <= 1041 <= nums[i] <= 104This approach uses the mathematical properties of numbers from 1 to n to determine the duplicate and missing numbers. Calculate the expected sum of numbers from 1 to n. Then, iterate through the array to find the actual sum of numbers and the sum of squares. By using these properties and equations, derive the duplicate and missing numbers.
This Python function calculates the missing and duplicate numbers using the sum and difference method. It computes the total expected and actual sums, as well as the sums of squares. These computations help solving linear equations to find the exact missing and duplicate numbers.
JavaScript
Time Complexity: O(n), as we iterate through the input array three times.
Space Complexity: O(1), since we use a constant amount of space for variables.
In this approach, utilize a hashmap to count the occurrences of each number. Iterate over the numbers from 1 to n and use the occurrence count to identify the duplicated and missing numbers.
This Java solution uses a HashMap to keep track of the count of each number. As we iterate over the range, we check the frequency of each number to determine which is duplicated and which is missing.
C#
Time Complexity: O(n), where n is the length of nums, due to two iterations over the array.
Space Complexity: O(n), for storing the counts in a hashmap.
| Approach | Complexity |
|---|---|
| Approach 1: Sum and Difference Method | Time Complexity: O(n), as we iterate through the input array three times. |
| Approach 2: Frequency Counting with HashMap | Time Complexity: O(n), where n is the length of nums, due to two iterations over the array. |
Set Mismatch - Leetcode 645 - Python • NeetCodeIO • 12,529 views views
Watch 9 more video solutions →Practice Set Mismatch with our built-in code editor and test cases.
Practice on FleetCodePractice this problem
Open in Editor