LeetCode-in-All
53. Maximum Subarray
Easy
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
object Solution {
def maxSubArray(nums: Array[Int]): Int = {
var maxi = Int.MinValue
var sum = 0
for (num <- nums) {
// calculating sub-array sum
sum += num
maxi = math.max(sum, maxi)
if (sum < 0) {
// there is no point in carrying a negative subarray sum; set it to 0
sum = 0
}
}
maxi
}
}