Two Phone Interviews

There are 4 questions in the first interview and only one question in the second interview.

Question 1: Count the number of set bits for a 32-bit integer. How to improve the process for the second time use if memory is unlimited?

Question 2: What is the output for the following code? int n = 1; puts(((char*)&n)[0]==1?"Y":"N");

Question 3: What are Encapsulation and Polymorphism?

Question 4: Forget.

Question 5: If there is a tree structure data, design an algorithm for a function next() which returns one data each time and this function will access all the data only once.

What is the output?

c int n = 1; puts(((char*)&n)[0]==1?"Y":"N");