Recently I got stuck on a question. Any help will be appreciated.

Question is -

You are given an old touch smartphone numbers having dial pad and calculator app. The goal is to type a number on dialpad. Calculator have **1-9** and **+, -, * , /, =** as operations. But as phone is old, some of the numbers and some operations can’t be touched. But you can always make a number using other numbers and operations. There could be multiple ways of making a number. You have to find minimum operation for making a number.

For ex: lets say **1,4,6,7,8,9** works and **+,-,*** works. **2,3,5** and **/** doesn’t work.

If you have to type **18-> 2** operations. (Each touch is considered an operation).

If you have to type **5 -> ‘1+4=’** that requires **4** operations. There could be other ways to make ‘5’.

The goal is to find minimum operations.