Initial value of B is 2 //value stored in main memory
Value of B = 4
First execute P2()
P2 ( ) {
D = 2 * B; // 2 × 2 = 4
B = D – 1; // B = 4 – 1 = 3
}
write the value of B = 3 to memory
execute P1()
P1 ( ) {
C = B – 1; // C = 3 – 1 = 2
B = 2 * C; // B = 2 × 2 = 4
}
write the value of B = 4 is memory.
Distinct value of B is 4.
Value of B =3
First Execute P1()
P1 ( ) {
C = B – 1; // C = 2 – 1 = 1
B = 2 * C; // B = 2 × 1 =2
}
write the value of B = 2 to memory
then execute P2()
P2 ( ) {
D = 2 * B; // 2 × 2 = 4
B = D – 1; // B = 4 – 1 = 3
}
write the value of B = 3 to memory
One of the distinct values of B is 3.
Value of B = 2
First execute P2()
P2 ( ) {
D = 2 * B; // 2 × 2 = 4
B = D – 1; // B = 4 – 1 = 3
}
//don’t write to memory
execute P1() // with initial value of B = 2
P1 ( ) {
C = B – 1; // C = 2 – 1 = 1
B = 2 * C; // B = 2 × 1 = 2
}
write the value B = 3 by P2() in memory.
overwrite the value written by P2() as B = 2 by P1() in memory.
One of the distinct values of B is 2.
Therefore, the distinct values of B are 2, 3 and 4.
The number of distinct values that B can possibly take after the execution is 3.
