Leetcode Maximum Subarray-----java

Find the contiguous subarray within an array (containing at least one number) which have the largest sum.

For example, given the array [−2,1,−3,4,−1,2,1,−5,4] ,
The contiguous Subarray has the [4,−1,2,1] largest sum = 6 .

The problem is to ask for the maximum substring and

Must be O (n) of Time and O (1) of space

is to add each time, 1, first to determine whether it is all non-positive, if so, then directly return the largest number.

2, and then add a number each time, then add in turn, if NUMS[J] is greater than 0, then compared with the result of large.

2, if at this time and less than 0, then leave, and I will be placed at this time the next bit of J.

public class Solution {public int maxsubarray (int[] nums) {if (nums.length = = 1) return nums[0];        int result = Nums[0],ans = Nums[0];        int i = 0,J = 1;        for (int k = 0;k<nums.length;k++) {if (Result < nums[k]) result = Nums[k];        } if (Result <= 0) return result; while (I<nums.length && J < nums.length) {if (Nums[i] < 0) {while (i<nums.                Length && nums[i]<0) i++;                if (i<nums.length) ans = nums[i];            j = i+1;        } else if (Nums[j] >= 0) {ans+=nums[j];        j + +;        result = result>ans?result:ans;        }else{if (Ans+nums[j] <= 0) {i = j+1;        j = j+2;        if (i<nums.length) ans = nums[i];        }else{Ans+=nums[j];        j + +;        }}} return result; }}

Then found to be in the writing is verbose. In fact, the following can

public class Solution {public    int maxsubarray (int[] nums) {        int max=nums[0];        for (int i=1;i<nums.length;++i) {            nums[i]=nums[i-1]<0? Nums[i]: nums[i-1]+nums[i];            max = Math.max (max, nums[i]);        }        return max;}    }

public class Solution {public    int maxsubarray (int[] nums) {if (nums.length = = 1) return nums[0];int presum = Nums[0];i NT max = nums[0];for (int i = 1; i < nums.length; i++) {if (presum <= 0) presum = nums[i];else {presum + = Nums[i];} if (Presum > Max) max = Presum;} return Max;}}

Leetcode Maximum Subarray-----java