53. Maximum Subarray.md

Problem Source

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

Problem Description

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

Example:

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

Thought

• Take care of negative values

Keypoints

• Array

Code

• Language: Java

class Solution {
    public int maxSubArray(int[] nums) {   
        int max = Integer.MIN_VALUE, sum = 0;
        for (int i = 0; i < nums.length; i++) {
            if (sum < 0) 
                sum = nums[i];
            else 
                sum += nums[i];
            if (sum > max)
                max = sum;
        }
        return max;
    }
}

Complexity

• Time Complexity：O(N)
• Space Complexity：O(1)