$[$Find the missing number$]$

$(8$ marks$)$ You are given an array of size $N-1$ consists of integers ranging from $1$ to $N.$ One of

the elements is missing from the given list. Assuming there are no duplicates in the list.

a$)$ Design an efficient algorithm to find the missing number in the given array $($Pseudocode$).$

b$)$ What is the time complexity of your algorithm

Note: The marks awarded will be proportional to the efficiency of the suggested algorithm.

Example:

Input: arr$=\{4,2,5,1\},N=5$

Output: $3$

Explanation: The missing number between $1$ to $5$ is $3$

ALGORITHM find$\_$missing$\_$Number $(arr,N)$

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