[Tip] Ceil (Round Up) & Floor (Round Down) 구현하기

[seungriyou]

x를 y로 나누는 상황에서, 결과 값의 올림과 내림을 구해보자.

Ceil (Round Up)

def ceil(x, y):
    return (x - 1) // y + 1

def ceil(x, y):
    q, r = divmod(x, y)
    return q + (1 if r else 0)

>>> ceil(5, 2)
3
>>> ceil(-5, 2)
-2

>>> ceil(6, 3)
2
>>> ceil(-6, 3)
-2

>>> ceil(5, 3)
2
>>> ceil(-5, 3)
-1

Floor (Round Down)

def floor(x, y):
    return x // y

>>> floor(5, 2)
2
>>> floor(-5, 2)
-3

>>> floor(6, 3)
2
>>> floor(-6, 3)
-2

>>> floor(5, 3)
1
>>> floor(-5, 3)
-2

Related Problems

• https://leetcode.com/problems/find-the-smallest-divisor-given-a-threshold/
• https://leetcode.com/problems/koko-eating-bananas/

References

• https://stackoverflow.com/questions/2745074/fast-ceiling-of-an-integer-division-in-c-c