# Python Easy MergeSort solution - Any chance a BST solution in Python?

• ``````class Solution(object):
def countRangeSum(self, nums, lower, upper):
"""
:type nums: List[int]
:type lower: int
:type upper: int
:rtype: int
"""
if len(nums) == 0:
return 0

from bisect import bisect_left, bisect_right
for i in range(1, len(nums)):
nums[i] += nums[i-1]
n = len(nums)
def mergeSort(nums, lo, hi):
if lo == hi:
return int(nums[lo] >= lower and nums[lo] <= upper), [nums[lo]]
mid = lo + (hi - lo) // 2
leftNums, leftList = mergeSort(nums, lo, mid)
rightNums, rightList = mergeSort(nums, mid+1, hi)
crossNums = 0
for x in leftList:
crossNums += bisect_right(rightList, x+upper) - bisect_left(rightList, x+lower)
totalList = []
i, j = 0, 0
while i < len(leftList) and j < len(rightList):
if leftList[i] < rightList[j]:
totalList.append(leftList[i])
i += 1
else:
totalList.append(rightList[j])
j += 1
totalList += rightList[j:] if i == len(leftList) else leftList[i:]
return leftNums+rightNums+crossNums, totalList
return mergeSort(nums, 0, n-1)[0]
``````

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