Day 10 of 100 Days LeetCode Challenge

LeetCode Challenge #268. Missing Number

Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

Example 1:

Input: nums = [3,0,1]
Output: 2
Explanation: n = 3 since there are 3 numbers, 
so all numbers are in the range [0,3].
2 is the missing number in the range since
it does not appear in nums.

Example 2:

Input: nums = [0,1]
Output: 2
Explanation: n = 2 since there are 2 numbers, 
so all numbers are in the range [0,2].
2 is the missing number in the range since
it does not appear in nums.

Example 3:

Input: nums = [9,6,4,2,3,5,7,0,1]
Output: 8
Explanation: n = 9 since there are 9 numbers, 
so all numbers are in the range [0,9].
8 is the missing number in the range since
it does not appear in nums.

Constraints:

  • n == nums.length
  • 1 <= n <= 104
  • 0 <= nums[i] <= n
  • All the numbers of nums are unique.
Video Solution
Java Solution
				
					class Solution {
    public int missingNumber(int[] nums) {
        int range = nums.length;
        int actualSum =  (range * (range + 1))/2;
        int currSum = 0 ;
        for(int i=0;i<nums.length;i++){
            currSum = currSum + nums[i];
        }
        int ans = actualSum - currSum ;
        return ans ;
    }
}
				
			
Pseudo Code of Solution
				
					Algorithm missingNumber(nums: Array of Integer) -> Integer
    Declare range as Integer
    Declare actualSum as Integer
    Declare currSum as Integer
    Declare ans as Integer

    // Calculate the range of the array
    range <- Length of nums

    // Calculate the sum of all numbers from 0 to range
    actualSum <- (range * (range + 1)) / 2

    // Initialize the sum of the elements in the array to 0
    currSum <- 0

    // Loop through the array to sum up its elements
    For i from 0 to Length of nums - 1 Do
        currSum <- currSum + nums[i]
    End For

    // Calculate the missing number
    ans <- actualSum - currSum

    // Return the missing number
    Return ans
End Algorithm

				
			

Happy Coding with edSlash