/*
 * @lc app=leetcode.cn id=303 lang=javascript
 *
 * [303] 区域和检索 - 数组不可变
 */

// @lc code=start
/**
 * @param {number[]} nums
 */
var NumArray = function (nums) {
  const n = nums.length;
  // 将长度设为 n + 1 是为了方便计算，不用特殊处理 0
  // sumRange(i, j) = arr[j + 1] - arr[i]
  this.arr = new Array(n + 1).fill(0)
  for (let i = 0; i < nums.length; i++) {
    this.arr[i + 1] = this.arr[i] + nums[i]
  }
};

/** 
 * @param {number} left 
 * @param {number} right
 * @return {number}
 */
NumArray.prototype.sumRange = function (left, right) {
  return this.arr[right + 1] - this.arr[left]
};

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

const numArray = new NumArray([-2, 0, 3, -5, 2, -1]);
console.log(numArray)
console.log(numArray.sumRange(0, 2)); // return 1 ((-2) + 0 + 3)
console.log(numArray.sumRange(2, 5)); // return -1 (3 + (-5) + 2 + (-1)) 
console.log(numArray.sumRange(0, 5)); // return -3 ((-2) + 0 + 3 + (-5) + 2 + (-1))