303.Range Sum Query(class、self的用法)

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.

Example:

Given nums = [-2, 0, 3, -5, 2, -1]

sumRange(0, 2) -> 1
sumRange(2, 5) -> -1
sumRange(0, 5) -> -3

Note:

You may assume that the array does not change.
There are many calls to sumRange function.

class NumArray:

    def __init__(self, nums):
        """
        :type nums: List[int]
        """
        self.nums = nums
        if len(nums):
            self.list = [nums[0]]
            for i in range(1,len(nums)):
                self.list.append(self.list[i-1]+nums[i])

    def sumRange(self, i, j):
        """
        :type i: int
        :type j: int
        :rtype: int
        """
        return self.list[j]-self.list[i]+self.nums[i]
        


# Your NumArray object will be instantiated and called as such:
# obj = NumArray(nums)
# param_1 = obj.sumRange(i,j)