```
class NumArray(object):
def __init__(self, nums):
"""
:type nums: List[int]
"""
self.cSum = [] # compute the cumulative sum of the array till current index
if len(nums) == 0:
pass
else:
self.cSum.append(nums[0])
if len(nums) > 1:
for num in nums[1:]:
temp = self.cSum[-1] + num
self.cSum.append(temp)
def sumRange(self, i, j):
"""
:type i: int
:type j: int
:rtype: int
"""
if i == 0:
return self.cSum[j]
else:
return self.cSum[j] - self.cSum[i-1]
# Your NumArray object will be instantiated and called as such:
# obj = NumArray(nums)
# param_1 = obj.sumRange(i,j)
```