Using shortcut:
It is mentioned that CSCAN algorithm to be used is the disk head will move in right direction ( i.e. disk head will move to cylinder will higher number). Initially the head is at cylinder 100.
Sequence of cylinder requests are 30,85,110,100,105,126,135,55,195.
On moving from 100 to 199, the cylinders 100, 105,110, 126,135,195 will be serviced. So number of cylinders traversed = 199-100 = 99.
Then disk head will return to 0th cylinder without servicing any cylinder. Number of cylinders traversed = 199-0 = 199
Among the remaining requests, which are 30, 55, 85, 85th cylinder is the highest cylinder. Therefore on traversing from 0th to 85th cylinder, all the requests will be serviced. Thus number of cylinders traversed = 85-0 = 85.
Total number of cylinders traversed or distanced traversed by R/W head using CSCAN algo = 99 + 199 + 85 = 383