a) A computer memory with a total of three physical pages with below page reference sequence: 1, 2, 3, 2, 1, 4, 3, 5, 6, 4, 3, 5, 3, 5, 6, 7, 2, 1, 5, 7. How many page faults occur using the following...

a) A computer memory with a total of three physical pages with below page
reference sequence: 1, 2, 3, 2, 1, 4, 3, 5, 6, 4, 3, 5, 3, 5, 6, 7, 2, 1, 5, 7.
How many page faults occur using the following algorithms?

a) FIFO
b) LRU
c) Optimal
Also state which one is better algorithm?