range-sum-query-immutable.js

// 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.


/**
 * @constructor
 * @param {number[]} nums
 */
var NumArray = function(nums) {
    this.arr = nums;
};

/**
 * @param {number} i
 * @param {number} j
 * @return {number}
 */
NumArray.prototype.sumRange = function(i, j) {

        var res = 0;
        for (var index = i; index <= j; index++) {
            res += this.arr[index];
        }
        return res;
};


/**
 * Your NumArray object will be instantiated and called as such:
 * var numArray = new NumArray(nums);
 * numArray.sumRange(0, 1);
 * numArray.sumRange(0, 2);
 */