01 max subarray.java

/*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.
*/
class Solution {
    public int maxSubArray(int[] nums) {
        int maxsum=nums[0];
        int currsum=0;
        for(int i=0;i<nums.length;i++)
            
        {
            currsum=currsum+nums[i];
            if(currsum>maxsum){
                maxsum=currsum;
            }
            if(currsum<0){
                currsum=0;
            }
        }
        return maxsum;
    }
}