Question

Optimise the following fragment of code to improve its speed and (b) explain your optimisations x := 0; read(y); unless x > 3 do y:= x + y; endunless write(y); In this fragment ' assigns its right-hand side to its left-hand side; reado) reads a numerical value from the input stream and assigns it to y; writeó) writes the printable form of y to the output stream. The unless loop terminates when its condition is met. 5 marks

Answer 1

Code:-

x := 4;

read(y)

y = y + (4*x);

write(y);

Explaination:-

For any value of y (input), the loop will only run for 4 iterations with incrementing 'x' in every iteration by '1' and adding 'x' to 'y'. So, 'x' becomes '4' and the loop stops as the condition 'x>3' is satisfied and also 'x' is added 4 times to the 'y'. Therefore:

x => 4

y => y + (4 * x)