Question

Write a program in Python to print all possible combinations of phone numbers. The length of the number will be given. Also 3 digits will be given, which can not be used. No two consecutive digits can be same. A number containing 4 would always have 4 in the beginning.

Answer 1

Code:

def checkCons(n):         #it will return True if two consecutive digits is not same
  for i in range(0,len(n)-1):
    if n[i] == n[i+1]:    #check two consecutive digits if same
      return False        #then return false
  return True       

length = int(input("Enter length of number : "))  #get length of phone number

a = int("1"*length)  #lower limit for given length
b = int("9"*length)  #upper limit for given length

Numbers=[]

# get 3 digits that will not present in number
d1 = str(input("Enter digit 1 : "))
d2 = str(input("Enter digit 2 : "))
d3 = str(input("Enter digit 3 : "))

for i in range(a,b+1):       #it will iterate from lower limit to upper limit
  num = str(i)               #convert number into string
  
  if (d1 not in num) and (d2 not in num) and (d3 not in num):#check any of given digit should not be present in number
    if (checkCons(num)):     #check two consecutive digits can not be same
      if "4" in num:         #if 4 in number 
        if (num[0] == "4"):  #then 4 is also in the begining
          Numbers.append(int(num)) #append number in list
      else:                   
         Numbers.append(int(num))   #append number in list

print("\nAll combinations of number is: ")
print(Numbers)

  
      
      

Output:

.