# 21. 最大子序和

java

```java
/**
 * 53.最大子序和.
 * 给定一个整数数组 nums ，找到一个具有最大和的连续子数组（子数组最少包含一个元素），返回其最大和。
 *
 * 示例:
 * 输入: [-2,1,-3,4,-1,2,1,-5,4],
 * 输出: 6
 * 解释: 连续子数组 [4,-1,2,1] 的和最大，为 6。
 *
 * 进阶:
 *
 * 如果你已经实现复杂度为 O(n) 的解法，尝试使用更为精妙的分治法求解。
 */
public class Solution53 {
    public int maxSubArray(int[] nums) {
        if (nums.length ==0) return 0;
        int sum = nums[0];
        int tmp=nums[0];
        for(int i=1;i<nums.length;i++){
            if(tmp>0){
                tmp+=nums[i];
                if(tmp>sum) sum=tmp;
            }else{
                tmp=nums[i];
                if(tmp>sum) sum=tmp;
            }
        }
        return sum;
    }

    public static void main(String[] args) {
        int[] nums = {
                -2, 1, -3, 4, -1, 2, 1, -5, 4
        };
        int r = new Solution53().maxSubArray(nums);
        System.out.println(r);
    }
}
```


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