Write code to find the minimum in the first half of an array and the maximum in the second half.
Implement find_half_extremes(nums). Return a two-element list containing the minimum value from the first half, followed by the maximum value from the second half. For odd-length arrays, the first half contains len(nums) // 2 elements and the second half contains the remaining elements.
Function signature: def find_half_extremes(nums):
def find_half_extremes(nums):