# 303.range-sum-query-immutable

## Statement

1. 计算索引 `left` 和 `right` （包含 `left``right`）之间的 `nums` 元素的 ，其中 `left <= right`

• `NumArray(int[] nums)` 使用数组 `nums` 初始化对象
• `int sumRange(int i, int j)` 返回数组 `nums` 中索引 `left` 和 `right` 之间的元素的 总和 ，包含 `left` 和 `right` 两点（也就是 `nums[left] + nums[left + 1] + … + nums[right]` )

``````输入：
["NumArray", "sumRange", "sumRange", "sumRange"]
[[[-2, 0, 3, -5, 2, -1]], [0, 2], [2, 5], [0, 5]]

[null, 1, -1, -3]

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

• `1 <= nums.length <= 104`
• `-105 <= nums[i] <= 105`
• `0 <= i <= j < nums.length`
• 最多调用 `104``sumRange` 方法

Given an integer array `nums`, handle multiple queries of the following type:

1. 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
``````

Constraints:

• `1 <= nums.length <= 104`
• `-105 <= nums[i] <= 105`
• `0 <= left <= right < nums.length`
• At most `104` calls will be made to `sumRange`.

## Solution

``````from typing import List

class NumArray:
def __init__(self, nums: List[int]):
self.sum = []
self.sum.append(0)
for a in nums:
self.sum.append(self.sum[-1] + a)

def sumRange(self, left: int, right: int) -> int:
return self.sum[right + 1] - self.sum[left]

# Your NumArray object will be instantiated and called as such:
# obj = NumArray(nums)
# param_1 = obj.sumRange(left,right)
``````