LC 53. Maximum Subarray

Alen Alex · February 12, 2024

LeetCode Link: 53. Maximum Subarray
Language: C#

Problem Statement

Given an integer array nums, find the subarray with the largest sum, and return its sum.

Examples

Example 1:

Input: nums = [-2,1,-3,4,-1,2,1,-5,4]
Output: 6
Explanation: The subarray [4,-1,2,1] has the largest sum 6.

Example 2:

Input: nums = [1]
Output: 1
Explanation: The subarray [1] has the largest sum 1.

Example 3:

Input: nums = [5,4,-1,7,8]
Output: 23
Explanation: The subarray [5,4,-1,7,8] has the largest sum 23.

Constraints

  • 1 <= nums.length <= 105
  • -104 <= nums[i] <= 104

Solution

public class Solution 
{
    public int MaxSubArray(int[] nums) 
    {
        if (nums.Length == 1)
        {
            return nums[0];
        }

        var sums = new int[nums.Length];
        var max = nums[0];
        sums[0] = nums[0];

        for (int i=1; i<nums.Length; i++)
        {
            var c = nums[i];
            var add = nums[i] + sums[i-1];
            sums[i] = Math.Max(c, add);
            max = Math.Max(max, sums[i]);
        }

        return max;
    }
}

Complexity

Time Complexity: O(N)
Space Complexity: O(N)

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