shortest job first algo

sjf.py

from __future__ import print_function, division
import os

job_list = []
id = 0

def calc_wt():
	temp = []
	for x in job_list:
		sum = 0
		for y in job_list[:job_list.index(x)]:
			sum += y[0]
		temp.append((x[1],sum))
	temp.sort()
	for x in temp:
		print('waiting time for process id', x[0],'is',x[1],sep=' ')

def calc_avg():
	temp = [x[0] for x in job_list]
	print('Average waiting time is',sum(temp)/len(temp),sep=' : ')

def get_process():
	global id
	os.system('clear')
	process_time = int(raw_input('Enter process time'))
	id += 1
	job_list.append((process_time,id))
	job_list.sort()

def show():
	os.system('clear')
	for time,id in job_list:
		print(id,time,sep='  ')

while 1:
	print('1. Enter','2. Show','3. Display Waiting time','4. Average waiting time','5. Exit',sep='\n')
	ch = int(raw_input())
	if ch == 1:
		get_process()
	elif ch == 2:
		show()
	elif ch == 3:
		calc_wt()
	elif ch == 4:
		calc_avg()
	elif ch == 5:
		print('Exiting....')
		exit()
	else:
		print('Wrong choice!!','Try again',sep='\n')