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LeetCode : 53. Maximum Subarray

2022-02-21
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LeetCode

53. Maximum Subarray

Problem

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

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

[1] Code (22. 02. 21) (x)

// Runtime: 1 ms
// Memory Usage: 51.6 MB
// Ref : https://leetcode.com/submissions/detail/645962717/
class Solution {
    public int maxSubArray(int[] nums) {
        int sum = 0;
        int cur = 0;
        int ans = nums[0];
        
        for (int i : nums) {
            cur = i;
            if (sum + cur < 0) {
                ans = Math.max(ans, cur);
                sum = cur < 0 ? 0 : cur;
            } else {
                sum += cur;
                ans = Math.max(ans, sum);
            }
        }
        
        return ans;
    }
}

Reference Code

Code 1

// Runtime: 2 ms
// Memory Usage: 89.7 MB
// Ref : https://leetcode.com/submissions/detail/611484077/
class Solution {
    public int maxSubArray(int[] nums) {
        int n = nums.length;
        int max = Integer.MIN_VALUE, sum = 0;

        for (int i = 0; i < n; i++) {
            sum += nums[i];
            max = Math.max(sum, max);

            if (sum < 0) {sum = 0;}
        }

        return max;
    }
}

Review

  • 20분 소요

    어렵지 않게 풀었다.

Reference

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