leetcode 303. Range Sum Query - Immutable | 303. 区域和检索 - 数组不可变（一维前缀和问题）

分手后的思念是犯贱 2022-10-13 05:28 204阅读 0赞

## 题目 ##

[https://leetcode.com/problems/range-sum-query-immutable/][https_leetcode.com_problems_range-sum-query-immutable]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70]

## 题解 ##

标准的前缀和问题，简单题，不多说，直接上代码

import java.util.Arrays;
    
    class NumArray { 
        int[] sum;
    
        public NumArray(int[] nums) { 
            sum = new int[nums.length + 1];
            sum[0] = 0;
            for (int i = 0; i < nums.length; i++) { 
                sum[i + 1] = sum[i] + nums[i];
            }
        }
    
        public int sumRange(int left, int right) { 
            return sum[right + 1] - sum[left];
        }
    }
    
    /** * Your NumArray object will be instantiated and called as such: * NumArray obj = new NumArray(nums); * int param_1 = obj.sumRange(left,right); */

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]

[https_leetcode.com_problems_range-sum-query-immutable]: https://leetcode.com/problems/range-sum-query-immutable/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70]: /images/20221005/4323877c1660403eba758483e2268674.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]: /images/20221005/05f1a6c0b51f4632a00769d2c50b899f.png