Maximum Subarray [LEETCODE]

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

For example, given the array [−2,1,−3,4,−1,2,1,−5,4],
the contiguous subarray [4,−1,2,1] has the largest sum = 6.

More practice:

If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.

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Consider an array A[i,....,j,j+1]. If we know its lagest subarrya is A[i,...,j].

Then the new array's lagest sum subarray may same as the array A[i,...j], or is A[i,...j,j+1].

That's only depends on if A[j+1] is larger than sum(A[i,...j]).

 

class Solution {
public:
    int maxSubArray(int A[], int n) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
       int max_sum = INT_MIN;
       int sum = 0;
       for(int i = 0; i < n; i++) {
           sum = max(sum + A[i], A[i]);
           max_sum = max(max_sum, sum);
       }
       return max_sum;

    }
};