Maximum Subarray

Description

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.

Solution(golang)

func MaxInt(a, b int) int {
    if a > b {
        return a
    }
    return b
}

func maxSubArray(nums []int) int {
    sum := nums[0]
    max := nums[0]
    for i:=1;i<len(nums);i++ {
        sum = MaxInt(sum + nums[i], nums[i])
        max = MaxInt(sum, max)
        sum = MaxInt(sum, 0)
    }
    return max
}