How to detect specific parts of a tuple?

Question

Working on a homework question which requires me to make a program which takes a set of tuple and detects if it counts as a domino cycle. For example, if given the tuples [(1,2),(2,3),(3,4)] , the program would return True . If an example like [(1,2),(3,4),(7,6)] is given it would return False . Also if only one set of tuple is given but both values within it is the same, for example [(5,5)] , True should be returned otherwise False , for example [(2,3)] . this is the part which I'm having issues with is getting the program to detect when a single tuple is given and wether the values inside it are the same. Also there are empty domino pieces in the game as well, I want the program to return True if an empty list is given such as "[]".

This is what I have so far and it just returns None when I try to run it for a single pair tuple. For multiple pairs of tuples, it works.

def cycle(tiles):
    for i in range(len(tiles)-1):
        tile1 = tiles[i]
        tile2 = tiles [i+1]

        if tile1[1:] == tile2[0:1] or ((tile1 and not tile2) or (not tile1 and not tile2)):
            return True
        else:
            return False

print (cycle([(4,4)]))

Answer 1

You didn't account for one tile case

def cycle(tiles):
    if len(tiles) == 0:
        return True
    if len(tiles) == 1:
        return tiles[0][0] == tiles [0][1]
    for i in range(len(tiles)-1):
        if  tiles[i][1] != tiles[i+1][0]:
            return False
    return True
print (cycle([(1,2),(2,3),(3,4)])) #True
print (cycle([(1,2),(5,3),(3,4)])) #False
print (cycle([(4,4)])) # True
print((cycle([(1,2),(2,3),(4,4)]))) #False

Answer 2

Working on a homework question which requires me to make a program which takes a set of tuple and detects if it counts as a domino cycle. For example, if given the tuples [(1,2),(2,3),(3,4)] , the program would return True . If an example like [(1,2),(3,4),(7,6)] is given it would return False . Also if only one set of tuple is given but both values within it is the same, for example [(5,5)] , True should be returned otherwise False , for example [(2,3)] . this is the part which I'm having issues with is getting the program to detect when a single tuple is given and wether the values inside it are the same. Also there are empty domino pieces in the game as well, I want the program to return True if an empty list is given such as "[]".

This is what I have so far and it just returns None when I try to run it for a single pair tuple. For multiple pairs of tuples, it works.

def cycle(tiles):
    for i in range(len(tiles)-1):
        tile1 = tiles[i]
        tile2 = tiles [i+1]

        if tile1[1:] == tile2[0:1] or ((tile1 and not tile2) or (not tile1 and not tile2)):
            return True
        else:
            return False

print (cycle([(4,4)]))

Answer 3

If time is not a factor, run two for loops to test for domino:

In [1]: m = [(1,2),(2,3),(3,4)]

In [2]: n = [(1,2),(3,4),(7,6)]

In [3]: all([i[1] == j[0] for i, j in zip(m[:-1], m[1:])])
Out[3]: True

In [4]: all([i[1] == j[0] for i, j in zip(n[:-1], n[1:])])
Out[4]: False

So the function should be:

def cycle(M):
    if not M:
        return True #will return True for empty list
    if len(M) == 1:
        return M[0] == M[1]
    return all(i[1] == j[0] for i, j in zip(M[:-1], M[1:]))

Answer 4

This should work:

dominoes=[(1,2),(1,3),(3,4),(4,5),(5,6)]
def isdomino(agg, item):
   #print(agg, item)
   if agg[0] == 1:
      if item[0] == item[1]:
         return 'True', ''
      else:
         return 'False', ''
   else:  
     if agg[0] == 'False':
       return 'False', ''
     if agg[1] == item[0]:
       return 'True', item[1]
     return 'False', item[1]

def checkdominoes(dominoes):
   if len(dominoes) == 0:
     return ('True', '')
   else:
     return reduce(isdomino, dominoes, (len(dominoes),dominoes[0][0]))


dominoes=[(1,2),(1,3),(3,4),(4,5),(5,6)]
something = checkdominoes(dominoes)
eval(something[0])
# False

dominoes=[(1,2),(2,3),(3,4),(4,5),(5,6)]
something = checkdominoes(dominoes)
eval(something[0])
# True

dominoes=[(1,2)]
something = checkdominoes(dominoes)
eval(something[0])
# False

dominoes=[(2,2)]
something = checkdominoes(dominoes)
eval(something[0])
# True

dominoes=[]
something = checkdominoes(dominoes)
eval(something[0])
# True