Fundamentals/Range Sum Query - Immutable
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Given an integer array nums, design a class NumArray that handles multiple queries of the following type:
  • Calculate the sum of the elements of nums between indices left and right inclusive, where left <= right.
Implement the NumArray class:
  • NumArray(int[] nums) initializes the object with the integer array nums.
  • int sumRange(int left, int right) returns the sum of the elements of nums between indices left and right inclusive (i.e., nums[left] + nums[left + 1] + ... + nums[right]).
The array nums is fixed at construction time and never changes. There may be many sumRange queries against the same array, so each query should be efficient.
Examples
Example 1
Input:
["NumArray", "sumRange", "sumRange", "sumRange"]
[[[-2, 0, 3, -5, 2, -1]], [0, 2], [2, 5], [0, 5]]
Output:
[null, 1, -1, -3]
Explanation:
NumArray numArray = new NumArray([-2, 0, 3, -5, 2, -1]);
numArray.sumRange(0, 2); // return (-2) + 0 + 3 = 1
numArray.sumRange(2, 5); // return 3 + (-5) + 2 + (-1) = -1
numArray.sumRange(0, 5); // return (-2) + 0 + 3 + (-5) + 2 + (-1) = -3
Constraints
  • 1 <= nums.length <= 10^4
  • -10^5 <= nums[i] <= 10^5
  • 0 <= left <= right < nums.length
  • At most 10^4 calls will be made to sumRange.