# # Task:
  * #### Complete the pattern, using the special character ```■   □```
  * #### In this kata, we draw some histogram of the sound performance of ups and downs.
# # Rules:
  -  parameter ```waves```  The value of sound waves, an array of number, all number in array >=0.
  -  return a string, ```■``` represents the sound waves, and ```□``` represents the blank part, draw the histogram from bottom to top.
# # Example:
```
draw([1,2,3,4])
□□□■
□□■■
□■■■
■■■■
draw([1,2,3,3,2,1])
□□■■□□
□■■■■□
■■■■■■
draw([1,2,3,3,2,1,1,2,3,4,5,6,7])
□□□□□□□□□□□□■
□□□□□□□□□□□■■
□□□□□□□□□□■■■
□□□□□□□□□■■■■
□□■■□□□□■■■■■
□■■■■□□■■■■■■
■■■■■■■■■■■■■
draw([5,3,1,2,4,6,5,4,2,3,5,2,1])
□□□□□■□□□□□□□
■□□□□■■□□□■□□
■□□□■■■■□□■□□
■■□□■■■■□■■□□
■■□■■■■■■■■■□
■■■■■■■■■■■■■
draw([1,0,1,0,1,0,1,0])
■□■□■□■□
```
def draw(waves):
    m = max(waves)
    return "\n".join("".join("□" if n < (m - row) else "■" for n in waves) for row in range(m))

def draw(waves):
    m = max(waves)
    return "\n".join("".join("□" if n < (m - row) else "■" for n in waves) for row in range(m))
