Leetcode53. 最大子数组和

题目传送地址: ​​https://leetcode.cn/problems/maximum-subarray/​​

代码如下:

class Solution {
  
   public static int maxSubArray(int[] nums) {
        int maxValue = Integer.MIN_VALUE;
        HashMap<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            int i1 = maxSubList(i, nums,map);
            if (i1 > maxValue) {
                maxValue = i1;
            }
        }
        return maxValue;

    }

    //以位置i的元素结尾，  的最大连续子数组之和
    public static int maxSubList(int i, int[] nums, Map<Integer, Integer> map) {
        int result;
        if (i == 0) {
            return nums[0];
        }
        int i1;
        if (map.containsKey(i-1)) {
            i1 = map.get(i-1);
        }else{
            i1 = maxSubList(i - 1, nums, map);
        }
        if (i1 > 0) {
            result = i1 + nums[i];
        } else {
            result = nums[i];
        }
        map.put(i,result);
        return result;
    }


}