import random

# divide and conquer to count negative values in list
def count_neg(list, first, last):
    #print 'count_neg(', first, ',', last, ')'
    ans = 0
    if first == last:
        if list[first] < 0:
            ans = 1
    elif first < last:
        mid = (first+last)/2
        left_ans = count_neg(list, first, mid)
        right_ans = count_neg(list, mid+1, last)
        ans = left_ans + right_ans
    else:
        print "uh oh, didn't expect first > last: ", first, last
    return ans

# divide and conquer to count both neg and pos values in list
# shows how a pair of vals (x,y) can be returned
def count_pos_neg(list, first, last):
    #print 'countmin(', first, ',', last, ')'
    pos = neg = 0
    if first == last:
        if list[first] < 0:
            neg = 1
        elif list[first] > 0:
            pos = 1            
    elif first < last:
        mid = (first+last)/2
        (neg_left,pos_left) = count_pos_neg(list, first, mid)
        (neg_right,pos_right) = count_pos_neg(list, mid+1, last)
        neg = neg_left + neg_right
        pos = pos_left + pos_right
    else:
        print "uh oh, didn't expect first > last: ", first, last
    return (neg,pos)    

# creates a random list
def random_list(n, min=0, max=9):
    list = [] # empty list
    for i in range(n):
        list.append( random.randint(min, max) )
    return list


def main():
    # list = input('Enter the list: ')
    list = random_list(8, -9, 9)
    print list
    num_neg = count_neg(list, 0, len(list)-1)
    print num_neg
    
    # variable pairs can be assigned values
    (num_neg, num_pos) = count_pos_neg(list, 0, len(list)-1)
    print num_neg, num_pos
    return

    
main()