天池 在线编程 两句话中的不常见单词（哈希计数）

0 <= A.length <= 200
0 <= B.length <= 200
A 和 B 都只包含空格和小写字母。

样例 1：
输入：A = "this apple is sweet", B = "this apple is sour"
输出：["sweet","sour"]

样例 2：
输入：A = "apple apple", B = "banana"
输出：["banana"]

class Solution:
    """
    @param A: Sentence A
    @param B: Sentence B
    @return: Uncommon Words from Two Sentences
    """
    def uncommonFromSentences(self, A, B):
        # Write your code here.
        wc = {}
        for w in A.split():
            if w in wc:
                wc[w] += 1
            else:
                wc[w] = 1
        for w in B.split():
            if w in wc:
                wc[w] += 1
            else:
                wc[w] = 1
        ans = []
        for w, c in wc.items():
            if c==1:
                ans.append(w)
        return ans