An approach using the XOR operator

• We can use the XOR operation which is safer than summation because in programming languages if the given input is large it may overflow and may give wrong answers.
• Before going to the solution, know that A xor A = 0. So if we XOR two identical numbers the value is 0.
• Now, XORing [1..n] with the elements present in the array cancels the identical numbers. So in the end we will get the missing number.

Have you wondered which is the most efficient way for a popular problem to find a missing Number? well in this post we are going to discuss this phenomenon in brief.

First, let’s discuss the problem statement:

Given an array of numbers from 1 to N (both inclusive). The size of the array is N-1. The numbers are randomly added to the array, there is one missing number in the array from 1 to N. What is the quickest way to find that missing number?