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
-spec max_sub_array(Nums :: [integer()]) -> integer().
-export([dp/4]).
max_sub_array(Nums) ->
N= length(Nums),
[Sum|Send] = Nums,
Max=Sum,
dp(Send,N-1,Sum,Max).
dp(Nums,0,Sum,Max)->
Max;
dp(Nums,N,Sum,Max) ->
[A|B] = Nums,
if
A+Sum > A -> Next = Sum+A;
true -> Next = A
end,
if
Next>Max -> Max2 = Next;
true -> Max2 = Max
end,
dp(B,N-1,Next,Max2).