441. Arranging Coins

難度:Easy

Python:

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def arrangeCoins(n):
    # r: 把第 1 ~ k 層塞滿會用到多少硬幣
    r = 0
    # k: 目前要塞的是第幾層
    k = 1
    while True:
        r += k     
        if r > n:
            return k - 1
        k += 1
            
class Solution:
    def arrangeCoins(self, n:int) -> int:
        return arrangeCoins(n)

Python 公式解:

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class Solution:
    def arrangeCoins(self, n: int) -> int:
        return (int)((2 * n + 0.25)**0.5 - 0.5)