372A - Counting Kangaroos is Fun - CodeForces Solution

def counting_kangaroos_is_fun():
    sizes = []
    for kangaroos in range(int(input())):
        sizes.append(int(input()))
    sizes.sort(reverse=True)
    half_length = len(sizes) // 2 + (len(sizes) // 2 * 2 < len(sizes))
    first_half, second_half = sizes[:half_length], sizes[half_length:]
    visible = len(sizes)
    a = 0
    b = 0
    while a < len(first_half) and b < len(second_half):
        if first_half[a] / 2 >= second_half[b]:
            visible -= 1
            a += 1
            b += 1
        elif b < len(second_half):
            b += 1
        else:
            break
    print(visible)


counting_kangaroos_is_fun()