Check if at least two out of three booleans are true

Question

An interviewer recently asked me this question: given three boolean variables, a, b, and c, return true if at least two out of the three are true.

My solution follow

Answer 1

This kind of questions can be solved with a Karnaugh Map:

      | C | !C
------|---|----
 A  B | 1 | 1 
 A !B | 1 | 0
!A !B | 0 | 0
!A  B | 1 | 0

from which you infer that you need a group for first row and two groups for first column, obtaining the optimal solution of polygenelubricants:

(C && (A || B)) || (A && B)  <---- first row
       ^
       |
   first column without third case