from collections import defaultdict

def collect_dictionary(obj):
  inv_obj = defaultdict(list)
  for key, value in obj.items():
    inv_obj[value].append(key)
  return dict(inv_obj)
  
ages = {
  'Peter': 10,
  'Isabel': 10,
  'Anna': 9,
}
collect_dictionary(ages) # { 10: ['Peter', 'Isabel'], 9: ['Anna'] }

def print_x_pattern(size):
    i,j = 0,size - 1

    while j >= 0 and i < size:

        initial_spaces = ' '*min(i,j)
        middle_spaces = ' '*(abs(i - j) - 1)
        final_spaces = ' '*(size - 1 - max(i,j))

        if j == i:
            print(initial_spaces + '*' + final_spaces)
        else:
            print(initial_spaces + '*' + middle_spaces + '*' + final_spaces)

        i += 1
        j -= 1

print_x_pattern(7)

# Deleting all even numbers from a list
a = [1,2,3,4,5]
del a[1::2]
print(a)

# Given a number n, print all primes smaller than or equal to n. It is also given that n is a small number.
# For example, if n is 10, the output should be “2, 3, 5, 7”. If n is 20, the output should be “2, 3, 5, 7, 11, 13, 17, 19”.


# Python program to print all primes smaller than or equal to
# n using Sieve of Eratosthenes

def SieveOfEratosthenes(n):
	
	# Create a boolean array "prime[0..n]" and initialize
	# all entries it as true. A value in prime[i] will
	# finally be false if i is Not a prime, else true.
	prime = [True for i in range(n + 1)]
	p = 2
	while (p * p <= n):
		
		# If prime[p] is not changed, then it is a prime
		if (prime[p] == True):
			
			# Update all multiples of p
			for i in range(p * 2, n + 1, p):
				prime[i] = False
		p += 1
	prime[0]= False
	prime[1]= False
	# Print all prime numbers
	for p in range(n + 1):
		if prime[p]:
			print (p)

# driver program
if __name__=='__main__':
    n = 30
    print("Following are the prime numbers smaller")
    print("than or equal to ", n)
    print("than or equal to ", n)
    SieveOfEratosthenes(n)

from itertools import product
V='∀'
E='∃'


def tt(f,n) :
  xss=product((0,1),repeat=n)
  print('function:',f.__name__)
  for xs in xss : print(*xs,':',int(f(*xs)))
  print('')

# p \/ (q /\ r) = (p \/ q) /\ (p \/ r)

def prob1(p,q,r) :
  x=p or (q and r)
  y= (p or q) and (p or r)
  return x==y

tt(prob1,3)

# p/\(q\/r)=(p/\q)\/(p/\r)

def prob2(p,q,r) :
  x=p and ( q or r )
  y=(p and q) or (p and r)
  return x==y

tt(prob2,3)

#~(p/\q)=(~p\/~q)

def prob3(p,q) :
  x=not (p and q)
  y=(not p) or (not q)
  return x==y
tt(prob3,2)

#(~(p\/q))=((~p)/\~q)

def prob4(p, q):
   x = not(p or q)
   y = not p and not q
   return x == y

tt(prob4, 2)

#(p/\(p=>q)=>q)

def prob5(p,q):
  x= p and ( not p or q)
  return not x or q
    
tt(prob5,2)

# (p=>q)=((p\/q)=q)

def prob6(p,q) :
  x = (not p or q)
  y=((p or q) == q)
  return x==y
 
tt(prob6,2)


#((p=>q)=(p\/q))=q
def prob7(p,q):
  if ((not p or q)==(p or q))==q:
    return 1
 
tt(prob7,2)



#(p=>q)=((p/\q)=p)
def prob8(p,q):
  if (not p or q)==((p and q)==p):
    return 1
 
tt(prob8,2)


#((p=>q)=(p/\q))=p

def prob9(p,q):
  if ((not p or q)==(p and q))==p:
    return '1'

tt(prob9,2)



#(p=>q)/\(q=>r)=>(p=>r)
def prob10(p,q,r) :
  x = not ((not p or q) and (not q or r)) or (not p or r)
  return x
 
tt(prob10, 3)


# (p = q) /\ (q => r)  => (p => r)
#answer 1
def prob11(p,q,r) :
  x = not((p is q) and (not q or r)) or (not p or r)
  return x
 
tt(prob11, 3)

#(p=q)/\(q=>r)=>(p=>r)
#answer 2
def prob11(p,q,r):
  x=(p==q) and (not q or r)
  y=not p or r
  return not x or y

tt(prob11,3)

#((p=>q)/\(q=r))=>(p=>r)

def prob12(p,q,r):
  x=(not p or q) and ( q==r )
  y=not p or r
  return not x or y

tt(prob12,3)

#(p=>q)=>((p/\r)=>(q/\r))

def prob13(p,q,r):
  x=not p or q
  y=(not(p and r) or ( q and r))
  return not x or y

tt(prob13,3)

#Question#2----------------------------------------

#(p=>q)=>r=p=>(q=>r)

def prob14(p,q,r):
  x=(not(not p or q) or r)
  y=(not p or (not q or r))
  return x==y

tt(prob14,3) 


def prob15(p, q):
    x = not(p and q)
    y = not p and not q
    return x == y

tt(prob15, 2)


def prob16(p, q):
    x = not(p or q)
    y = not p or not q
    return x == y

tt(prob16, 2)



def prob17(p):
    x = p
    y = not p
    return x == y

tt(prob17, 1)

def check_prop(fn, prop):
  return lambda obj: fn(obj[prop])
  
check_age = check_prop(lambda x: x >= 18, 'age')
user = {'name': 'Mark', 'age': 18}
check_age(user) # True