The dice problem

You are given a cubic dice with 6 faces. All the individual faces have a number printed on them. The numbers are in the range of 1 to 6, like any ordinary dice. You will be provided with a face of this cube, your task is to guess the number on the opposite face of the cube.

Examples:

Input: n = 2
Output: 5
Explanation: For dice facing number 5 opposite face will have the number 2.

Input: n = 6
Output: 1
Explanation: For dice facing number 6 opposite face will have the number 1.

[Naive Approach] Using if-else Statement

In a normal 6-faced dice, 1 is opposite to 6, 2 is opposite to 5, and 3 is opposite to 4. Hence a normal if-else-if block can be placed 

5

Time Complexity: O(1)
Auxiliary Space: O(1)

[Expected Approach] Using Sum of Two Sides

The idea is based on the observation that the sum of two opposite sides of a cubical dice is equal to 7. So, just subtract the given n from 7 and print the answer.

5

Time Complexity: O(1)
Auxiliary Space: O(1)