题解 | #选牛比赛#

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param digits string字符串一维数组 
# @param n int整型 
# @return int整型
#
class Solution:
    def countEligibleCows(self , digits: List[str], n: int) -> int:
        # write code here
        n_str = str(n)
        n_len = len(n_str)
        digits_count = len(digits)

        # 计算长度小于 n_str 长度的所有合法编号数量
        total = 0
        for length in range(1, n_len):
            total += digits_count ** length

        # 计算长度等于 n_str 长度的合法编号数量
        i = 0
        while i < n_len:
            j = 0
            while j < digits_count:
                if int(digits[j]) < int(n_str[i]):
                    if i == n_len - 1:
                        total += 1
                    else:
                        total += (digits_count ** (n_len - i - 1))
                elif int(digits[j]) == int(n_str[i]):
                    if i == n_len - 1:
                        total += 1
                    else:
                        i += 1
                        j = -1
                j += 1
            i += 1

        return total