find longest subarray by sum

def max_length(s, k):<br /> current = []<br /> max_len = -1 # returns -1 if there is no subsequence that adds up to k.<br /> for i in s:<br /> current.append(i)<br /> while sum(current) > k: # Shrink the array from the left, until the sum is <= k.<br /> current = current[1:]<br /> if sum(current) == k:<br /> max_len = max(max_len, len(current))</p> <p> return max_len