Leetcode: Range Sum Query – Immutable Posted on January 12, 2018September 10, 2019 by braindenny Range Sum Query – Immutable Similar Problems: CheatSheet: Leetcode For Code Interview Tag: #oodesign, #concurrency 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. Github: code.dennyzhang.com Credits To: leetcode.com Leave me comments, if you have better ways to solve. ## Blog link: https://code.dennyzhang.com/range-sum-query-immutable class NumArray(object): def __init__(self, nums): """ :type nums: List[int] """ length = len(nums) self._nums = nums self._sum = [0] * length sum_value = 0 for i in range(0, length): sum_value += nums[i] self._sum[i] = sum_value def sumRange(self, i, j): """ :type i: int :type j: int :rtype: int """ return self._sum[j] - (self._sum[i-1] if i>0 else 0) # Your NumArray object will be instantiated and called as such: # obj = NumArray(nums) # param_1 = obj.sumRange(i,j) Post Views: 6