# Statement => write in the function.

# output the string and number
# puts is output and \n
# output is output only.
puts "Hello world!!" # => Hello world!!\n
puts "number = ", 65536 # => number = 65536\n
output "not new line" # => not new line

# declaration is not required
# support only integer
i = 10
i = i + 43
i = i % 5
i = i - 32
sum = i * (12 / 5)
12 / 5 # => 2

# loop and if
for i = 1, i < 100, i = i + 1
    if i % 15 == 0
        puts "fizzbuzz"
    elsif i % 5 == 0
        puts "buzz"
    elsif i % 3 == 0
        puts "fizz"
    else
        puts i
    end
end

# create function
def sum(n)
    sm = 0
    for i = 1, i <= n, i = i + 1
        sm = sm + i
    end
    sm
    # "return sm" is OK
end

def fib(n)
    if n < 2
        n
    else
        fib(n - 1) + fib(n - 2)
    end
end

puts fib(39)

def sort(a, left, right)
    l = left; r = right; pv = a[(l + r) / 2]
    while 1
        while a[l] < pv; l++; end
        while pv < a[r]; r--; end
        if l >= r; break end
        tmp = a[l]; a[l] = a[r]; a[r] = tmp
        l++; r--;
    end
    l--; r++
    if left < l; sort(a, left, l); end
    if r < right; sort(a, r, right); end
end