rangeSumQueryImmutable.js

////////////////////////////////////////////////Range Sum Query - Immutable///////////////////////////////////////////
// Given an integer array nums, handle 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]).
// 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
/**
 * @param {number[]} nums
 */
 const NumArray = function(nums) {
    this.sums = [];
    let sum = 0;
    for (let i = 0; i < nums.length; i++) {
        sum += nums[i];
        this.sums.push(sum);
    }
};

/**
 * @param {number} left
 * @param {number} right
 * @return {number}
 */
NumArray.prototype.sumRange = function(left, right) {
    return this.sums[right] - (left > 0 ? this.sums[left - 1] : 0);
};

/**
 * Your NumArray object will be instantiated and called as such:
 * var obj = new NumArray(nums)
 * var param_1 = obj.sumRange(left,right)
 */