【leetcode】1347. Minimum Number of Steps to Make Two Strings Anagram

题目如下：

Given two equal-size strings s and t. In one step you can choose any character of t and replace it with another character.

Return the minimum number of steps to make t an anagram of s.

An Anagram of a string is a string that contains the same characters with a different (or the same) ordering.

Example 1:
Input: s = "bab", t = "aba"
Output: 1
Explanation: Replace the first 'a' in t with b, t = "bba" which is anagram of s.
Example 2:
Input: s = "leetcode", t = "practice"
Output: 5
Explanation: Replace 'p', 'r', 'a', 'i' and 'c' from t with proper characters to make t anagram of s.
Example 3:
Input: s = "anagram", t = "mangaar"
Output: 0
Explanation: "anagram" and "mangaar" are anagrams. 
Example 4:
Input: s = "xxyyzz", t = "xxyyzz"
Output: 0
Example 5:
Input: s = "friend", t = "family"
Output: 4
Constraints:

1 <= s.length <= 50000

s.length == t.length

s and t contain lower-case English letters only.

解题思路：只要求出s和t之间差异的字符的数量即可。

代码如下：

class Solution(object):
    def minSteps(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: int
        """
        val = [0] * 26;
        res = 0;
        for i in s:
            val[ord(i) - ord('a')] += 1
        
        for i in t:
            val[ord(i) - ord('a')] -= 1  
   
        for i in val:
            if i > 0:
                res += i
        return res