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
class Solution {
int maxSubArray(List<int> nums) {
int maxi = -1 << 31; // Equivalent to Integer.MIN_VALUE
int sum = 0;
for (int num in nums) {
// calculating sub-array sum
sum += num;
maxi = sum > maxi ? sum : maxi;
if (sum < 0) {
// reset sum to 0 if it's negative
sum = 0;
}
}
return maxi;
}
}