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.

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.

 

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 = [0]
Output: 0

Example 4:

Input: nums = [-1]
Output: -1

Example 5:

Input: nums = [-2147483647]
Output: -2147483647

 

Constraints:

• 1 <= nums.length <= 2 * 104
• -231 <= nums[i] <= 231 - 1

Solution(javascript)

/** Bottom-up
 * @param {number[]} nums
 * @return {number}
 */
const maxSubArray = function (nums) {
  let max = -Infinity
  let currentMax = -Infinity
  for (let i = 0; i < nums.length; i++) {
    currentMax = Math.max(
      currentMax + nums[i],
      nums[i],
    )
    max = Math.max(max, currentMax)
  }
  return max
}
// @lc code=end