# 0053. Maximum Subarray

<https://leetcode.com/problems/maximum-subarray>

## Description

Given an integer array `nums`, find the contiguous subarray (containing at least one number) which has the largest sum and return *its sum*.

A **subarray** is a **contiguous** part of an array.

**Example 1:**

```
**Input:** nums = [-2,1,-3,4,-1,2,1,-5,4]
**Output:** 6
**Explanation:** [4,-1,2,1] has the largest sum = 6.
```

**Example 2:**

```
**Input:** nums = [1]
**Output:** 1
```

**Example 3:**

```
**Input:** nums = [5,4,-1,7,8]
**Output:** 23
```

**Constraints:**

* `1 <= nums.length <= 105`
* `-104 <= nums[i] <= 104`

**Follow up:** If you have figured out the `O(n)` solution, try coding another solution using the **divide and conquer** approach, which is more subtle.

## ac

```java
class Solution {
    public int maxSubArray(int[] nums) {
        // edge case
        if (nums == null || nums.length == 0) return 0;

        int maxSum = Integer.MIN_VALUE, tmpSum = 0;
        for (int i = 0; i < nums.length; i++) {
            tmpSum += nums[i];
            maxSum = Math.max(maxSum, tmpSum);
            if (tmpSum < 0) tmpSum = 0;
        }

        return maxSum;
    }
}
```