# Write a function that accepts an array of integers and returns the indices for
# the starting and ending integers that, if their elements were sorted, the
# entire array would be sorted.
################################################################################
# First Attempt
################################################################################
def unsorted_substring(xs):
ys = xs[:]; ys.sort()
m = 0
while xs[m] == ys[m]:
m += 1
if m >= len(xs):
return -1, -1
n = len(xs) - 1
while xs[n] == ys[n]:
n -= 1
return m, n
################################################################################
# Second Attempt
################################################################################
def unsorted_substring_2(xs):
beg = 1
while xs[beg - 1] <= xs[beg]:
beg += 1
if beg >= len(xs):
return -1, -1
end = len(xs) - 2
while xs[end + 1] >= xs[end]:
end -= 1
min_mid = xs[beg]
max_mid = xs[beg]
i = beg + 1
while i <= end:
min_mid = min(min_mid, xs[i])
max_mid = max(max_mid, xs[i])
i += 1
# beg -= 1 until max(lhs) <= min(mid)
while beg - 1 >= 0 and xs[beg - 1] >= min_mid:
beg -= 1
# end += 1 while max(mid) <= min(rhs)
while end + 1 < len(xs) and max_mid >= xs[end + 1]:
end += 1
return beg, end
################################################################################
# Tests
################################################################################
xs = [
[1,2,4,7,10,11,7,12,6,7,16,18,19],
[1,2,3,4],
[4,3,2,1],
[1,3,2,4],
[2,1,3,4],
]
for x in xs:
print("Testing: {}".format(x))
print("1) {}".format(unsorted_substring(x)))
print("2) {}".format(unsorted_substring_2(x)))
