天翼云技术B卷编程题

1、丑数

题目：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。
python代码：

class Solution:
    def getnumber(self,index):
        res = []
        for k in range(15):
            for j in range(20):
                for i in range(30):
                    res.append(2**i*3**j*5**k)
        res.sort()
        print(res)
        if index:
            return res[index-1]
        else:
            return 0
if __name__ == '__main__':
    s = Solution()
    n = input().strip()
    res = s.getnumber(int(n))
    print(res)

2、删除出现次数最小的字符

python代码：

def removechar(s):
    dic = {}
    for i in s:
        if i in dic:
            dic[i] += 1
        else:
            dic[i] = 1
    for j in dic:
        if dic[j] == min(dic.values()):
            s = s.replace(j,"")
    return s
if __name__ == '__main__':
    s = input()
    print(removechar(s))

3、最小栈

python代码：

class Solution:
    def __init__(self):
        self.stack = []
    def push(self,x):
        if not self.stack:
            self.stack.append((x,x))
        else:
            self.stack.append((x,min(x,self.stack[-1][1])))
    def pop(self):
        self.stack.pop()
    def top(self):
        return self.stack[-1][0]
    def getMin(self):
        return self.stack[-1][1]
if __name__ == '__main__':
    s = Solution()
    n = input().strip()
    for i in range(int(n)):
        c1 = input().split()
        if c1[0] == "push":
            s.push(int(c1[1]))
        elif c1[0] == "pop":
            s.pop()
        elif c1[0] == "top":
            print(s.top())
        elif c1[0] == "getMin":
            print(s.getMin())