leetcode Trapping Rain Water pthon

class Solution(object):

    def trap(self,nums):

        leftmosthigh = [0 for i in range(len(nums))]

        leftmax=0

        for i in range(len(nums)):

            if nums[i] > leftmax:

                leftmax=nums[i]

            leftmosthigh[i] = leftmax

        print leftmosthigh

        sums=0

        rightmax=0

        for i in reversed(range(len(nums))):

            print i

            if nums[i] > rightmax:

                rightmax = nums[i]

            print 'i is',i,'rightmax is',rightmax

            #current i less than it's two side, then it can trap

            if min(rightmax,leftmosthigh[i] ) > nums[i]:

                sums+=min(rightmax,leftmosthigh[i])-nums[i]

        return sums

nums= [0,1,0,2,1,0,1,3,2,1,2,1]

obj=Solution()

rs=obj.trap(nums)

print rs