Leetcode: Range Sum Query - Immutable

Question

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.

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Hide Similar Problems (M) Range Sum Query 2D - Immutable (M) Range Sum Query - Mutable

My Solution

Accept

[code]class NumArray(object):
    def __init__(self, nums):
        """
        initialize your data structure here.
        :type nums: List[int]
        """

        if len(nums)!=0:
            self.sum = [0]*len(nums)
            self.sum[0] = nums[0]
            for ind in range(1,len(nums)):
                self.sum[ind] = self.sum[ind-1] + nums[ind]
        else:
            self.sum = -1

    def sumRange(self, i, j):
        """
        sum of elements nums[i..j], inclusive.
        :type i: int
        :type j: int
        :rtype: int
        """

        if i>j or self.sum==-1:
            return 0

        if i==0:
            return self.sum[j]

        return self.sum[j] - self.sum[i-1]

# Your NumArray object will be instantiated and called as such:
# numArray = NumArray(nums)
# numArray.sumRange(0, 1)
# numArray.sumRange(1, 2)