```
def increasingTriplet(self, nums):
if len(nums)<3:return False
a,b=None,None
for i in range(1,len(nums)):
if nums[i]<=nums[i-1]:continue #find inflection point
if a is None or b is None:a,b=nums[i-1],nums[i]
else:
if nums[i]>b or nums[i-1]>a:return True
a,b=nums[i-1],nums[i]
return False
```