LeetCode 268: Missing Number Solution

Problem Explanation

Explanation:

To find the missing number in the array, we can utilize the property of the sum of the first n natural numbers. The sum of the first n natural numbers is given by the formula: n * (n + 1) / 2. By calculating the expected sum of numbers in the range [0, n] and subtracting the sum of the elements in the array, we can find the missing number.

Algorithm:

Calculate the expected sum of numbers in the range [0, n] using the formula n * (n + 1) / 2.
Calculate the actual sum of elements in the array.
Subtract the actual sum from the expected sum to find the missing number.

Time Complexity:

The time complexity of this algorithm is O(n) since we iterate through the array once to calculate the sum.

Space Complexity:

The space complexity of this algorithm is O(1) as we are not using any extra space other than a few variables.

Solution Code

class Solution {
    public int missingNumber(int[] nums) {
        int n = nums.length;
        int expectedSum = n * (n + 1) / 2;
        int actualSum = 0;
        
        for (int num : nums) {
            actualSum += num;
        }
        
        return expectedSum - actualSum;
    }
}

Frequently Asked Questions

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What is the time complexity of LeetCode 268 (Missing Number)?

The time complexity for LeetCode 268 (Missing Number) varies by solution. Check the detailed explanation section for specific complexities in Java, C++, and Python implementations.

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268. Missing Number