leetcode 643. Maximum Average Subarray I | 643. 子数组最大平均数 I（Java）

￡神魔★判官ぃ 2022-10-05 03:57 132阅读 0赞

## 题目 ##

[https://leetcode-cn.com/problems/maximum-average-subarray-i/][https_leetcode-cn.com_problems_maximum-average-subarray-i]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70]

## 题解 ##

滑动窗口解法，示意图：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]  
另外，double 计算比 int 要慢，所以中间记录的值要设成 int 型，最后返回的时候再转换成 double

class Solution { 
        public double findMaxAverage(int[] nums, int k) { 
            int maxSum = 0;
            int curSum = 0;
            // init
            for (int i = 0; i < k; i++)
                curSum += nums[i];
            maxSum = curSum;
            // update
            for (int i = 0; i < nums.length - k; i++) { 
                curSum = curSum - nums[i] + nums[i + k];
                maxSum = Math.max(curSum, maxSum);
            }
            return (double) maxSum / k;
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 2]

[https_leetcode-cn.com_problems_maximum-average-subarray-i]: https://leetcode-cn.com/problems/maximum-average-subarray-i/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70]: /images/20221005/aaf538698c6d42908364ac02fb710fcf.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]: /images/20221005/bf60e202688149ee8d9e382d2d3a37ff.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 2]: /images/20221005/d4d2b43fa4124cc4a355691abc4a3b25.png