Given an array of integers, find a contiguous subarray which has the largest sum.
Example
For example, given the array [−2,2,−3,4,−1,2,1,−5,3], the contiguous subarray [4,−1,2,1] has the largest sum = 6.
Note
The subarray should contain at least one number
Challenge
Can you do it in time complexity O(n)?
Solution: O(n) time O(1) space. one pass. Prefix Sum
public int maxSubArray(ArrayList<Integer> nums) {
if (nums == null || nums.size() == 0) {
return 0;
}
int maxSum = Integer.MIN_VALUE;
int sum = 0;
int minSum = 0;
for (Integer num : nums) {
sum += num;
maxSum = Math.max(maxSum, sum - minSum);
minSum = Math.min(minSum, sum);
}
return maxSum;
}
