Let A[1n] be an array of n positive and negative numbers. The minimum subarray of A is a contiguous subarray of A which has the smallest sum. Please give the divide-and-conquer algorithm to compute the sum of the minimum subarray of A in O(nlog n) time. For example, if the given array is {-3, 5, -2, 1, -4, -7, 9, -6, 2}, then the minimum subarray of A is {-2, 0, -4, -7} and the output is their sum -13.

Please briefly describe your idea, give pseudocode if necessary, give the recurrence and conclude the time complexity. You do not need to show how to solve the recurrence to get the running time complexity.