Find all continuous reverse pair.

The minimum of pair[1] is the minimum of sorted list and the maximum of pair[0] is the maximum of sorted list.

```
def findUnsortedSubarray(self, l):
reverse = filter(lambda p: p[0] > p[1], zip(l, l[1:]))
if not reverse: return 0
left, right = min(p[1] for p in reverse), max(p[0] for p in reverse)
for i in xrange(len(l)):
if l[i] > left: break
for j in xrange(len(l)):
if l[-j-1] < right: break
return len(l) - j - i
```