leetcode刷题记录9-11

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介绍9

Related to question Excel Sheet Column Title

Given a column title as appear in an Excel sheet, return its corresponding column number.

For example:

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A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28

思路9

利用python内置函数把字母转化为数字

代码9

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class Solution(object):
    def titleToNumber(self, s):
        """
        :type s: str
        :rtype: int
        """
        n=0
        t=len(s)
        for i in s:
            t=t-1
            n=n+(ord(i)-64)*26**t
        return n

介绍10

Given two strings s and t, write a function to determine if t is an anagram of s.

For example,
s = “anagram”, t = “nagaram”, return true.
s = “rat”, t = “car”, return false.

Note:
You may assume the string contains only lowercase alphabets.

Follow up:
What if the inputs contain unicode characters? How would you adapt your solution to such case?

思路10

简单粗暴，既然差别只在于字母的顺序，那就统一重新排序好了

代码10

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class Solution(object):
    def isAnagram(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: bool
        """
        s=list(s)
        t=list(t)
        s.sort()
        t.sort()
        return s==t

介绍11

Given a non-negative integer n, count all numbers with unique digits, x, where 0 ≤ x < 10n.

Example:
Given n = 2, return 91. (The answer should be the total numbers in the range of 0 ≤ x < 100, excluding [11,22,33,44,55,66,77,88,99])

思路11

找出递归规律就行了

代码11

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class Solution(object):
    def countNumbersWithUniqueDigits(self, n):
        """
        :type n: int
        :rtype: int
        """
        if n==0:
            return 1
        elif n==1:
            return 10
        else:
            t=[9-i for i in range(n-1)]
            t=[1]+t
            for i in range(n):
               if i==0:
                  pass
               else:
                  t[i]=t[i]*t[i-1]
            t=[9*i for i in t]
            t=[1]+t
            for i in range(n+1):
               if i==0:
                  pass
               else:
                  t[i]=t[i]+t[i-1]
            return t[-1]