当前位置： 面试刷题>> 最大子数组差 (经典算法题500道)
### 题目描述补充
**题目：最大子数组差**
给定一个整数数组 `nums`，你需要找到该数组中的一个子数组（连续的元素序列），使得该子数组的最大值与最小值之差尽可能大。返回这个最大差值。
**示例 1**:
```
输入: nums = [5, 2, 9, 1]
输出: 7
解释: 子数组 [5, 2, 9] 的最大值为 9，最小值为 2，差值为 9 - 2 = 7。
```
**示例 2**:
```
输入: nums = [1, 3, 5, 4, 2, 8, 6, 7]
输出: 6
解释: 子数组 [3, 5, 4, 2, 8] 的最大值为 8，最小值为 2，差值为 8 - 2 = 6。
```
**注意**：
- 数组长度在 `[2, 10^5]` 范围内。
- 数组中的元素在 `[-10^9, 10^9]` 范围内。
### PHP 示例代码
```php
function maximumSubarrayDifference($nums) {
$n = count($nums);
$maxDiff = PHP_INT_MIN;
$currentMin = PHP_INT_MAX;
$currentMax = PHP_INT_MIN;
$currentDiff = 0;
for ($i = 0; $i < $n; $i++) {
$currentMin = min($currentMin, $nums[$i]);
$currentMax = max($currentMax, $nums[$i]);
$currentDiff = max($currentDiff, $currentMax - $currentMin);
// 如果当前最大值减去当前最小值小于等于之前计算的最大差值，
// 则考虑以当前元素为新的子数组起点，重置当前最小值和最大值
if ($nums[$i] - $currentMin >= $currentDiff) {
$currentMin = $nums[$i];
$currentMax = $nums[$i];
}
$maxDiff = max($maxDiff, $currentDiff);
}
return $maxDiff;
}
// 示例
$nums = [5, 2, 9, 1];
echo maximumSubarrayDifference($nums); // 输出 7
```
### Python 示例代码
```python
def maximumSubarrayDifference(nums):
max_diff = float('-inf')
current_min = float('inf')
current_max = float('-inf')
current_diff = 0
for num in nums:
current_min = min(current_min, num)
current_max = max(current_max, num)
current_diff = max(current_diff, current_max - current_min)
# 优化：如果当前元素减去当前最小值大于等于当前差值，则重置当前最小值和最大值
if num - current_min >= current_diff:
current_min = num
current_max = num
max_diff = max(max_diff, current_diff)
return max_diff
# 示例
nums = [5, 2, 9, 1]
print(maximumSubarrayDifference(nums)) # 输出 7
```
### JavaScript 示例代码
```javascript
function maximumSubarrayDifference(nums) {
let maxDiff = -Infinity;
let currentMin = Infinity;
let currentMax = -Infinity;
let currentDiff = 0;
for (let num of nums) {
currentMin = Math.min(currentMin, num);
currentMax = Math.max(currentMax, num);
currentDiff = Math.max(currentDiff, currentMax - currentMin);
// 优化：如果当前元素减去当前最小值大于等于当前差值，则重置当前最小值和最大值
if (num - currentMin >= currentDiff) {
currentMin = num;
currentMax = num;
}
maxDiff = Math.max(maxDiff, currentDiff);
}
return maxDiff;
}
// 示例
const nums = [5, 2, 9, 1];
console.log(maximumSubarrayDifference(nums)); // 输出 7
```
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