【剑指offer】34. 丑数(python)

题目描述

把只包含质因子2、3和5的数称作丑数（Ugly Number）。例如6、8都是丑数，但14不是，因为它包含质因子7。 习惯上我们把1当做是第一个丑数。求按从小到大的顺序的第N个丑数。

思路

《剑指offer》P182
从小到大依次所有的丑数，并保存。

code

# -*- coding:utf-8 -*-
class Solution:
    def GetUglyNumber_Solution(self, index):
        # write code here
        if index == 1 or index == 0:
            return index
        numbers = [1]
        number2 = numbers[0] * 2
        number3 = numbers[0] * 3
        number5 = numbers[0] * 5
        n2 = 0
        n3 = 0
        n5 = 0
        while len(numbers) < index:
            minNumber = self.minInNumbers(number2, number3, number5)
            numbers.append(minNumber)
            if minNumber == number2:
                n2 += 1
                number2 = numbers[n2] * 2
            if minNumber == number3:
                n3 += 1
                number3 = numbers[n3] * 3
            if minNumber == number5:
                n5 += 1
                number5 = numbers[n5] * 5
        return numbers[len(numbers) - 1]

    def minInNumbers(self, x1, x2, x3):
        tmp = x1
        if x1 > x2:
            tmp = x2
        if x3 > tmp:
            return tmp
        else:
            return x3