LeetCode-in-All
53. Maximum Subarray
Medium
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
defmodule Solution do
@spec max_sub_array(nums :: [integer]) :: integer
def max_sub_array([h | t]) do
solve(t, h, h)
end
defp solve([], curr_sum, max_sum), do: max(curr_sum, max_sum)
defp solve(nums, curr_sum, max_sum) when curr_sum < 0 do
solve(nums, 0, max_sum)
end
defp solve([h | t], curr_sum, max_sum) do
curr_sum = curr_sum + h
solve(t, curr_sum, max(curr_sum, max_sum))
end
end