Python list of integers as input and searches for a 'symmetrical' inner-portion of the list.
def symmetrical_sum(a):
'''Takes a Python list of integers as input and searches for a 'symmetrical' inner-portion of the list
Example: symmetrical_sum([10,8,7,5,9,8,15]) == ([8, 7, 5, 9, 8], 37)
Symmetry occurs if the value of the ith element at the start of the list is equal to the value of the
ith element at the end of the list'''
#extract duplicate value
dupe = [x for n, x in enumerate(a) if x in a[:n]]
#if no duplicate values found, do the following:
if dupe == []:
middle = float(len(a))/2
if middle % 2 != 0:
sym = a[int(middle - .5):int(middle + .5)]
ans = a[int(middle - .5)]
tuple1 = (sym,ans)
elif middle % 2 == 0:
sym = a[int(middle - 1):int(middle + 1)]
ans = sum(a[int(middle - 1):int(middle + 1)])//2
tuple1 = (sym,ans)
return tuple1
else:
d_to_i = int("".join(map(str, dupe))) #convert duplicate value to integer
p1 = a.index(d_to_i) #get index of first duplicate
p2 = a.index(d_to_i, p1+1) #get index of second duplicate
sym = a[p1:p2+1] #[symmetrical-portion]
ans = sum(sym) #sum-of-symmetrical-portion
tuple2 = (sym, ans)
return tuple2