字典的练习题——重复单词的统计

示例：用户输入一句英文句子，打印出每个单词及其重复的次数，重复的单词：此处认为单词之间以空格为分隔符，并且不包含,和.

举例：输入：“hello java hello python”

           输出：hello 2 

                       java 1

                       python 1

s = raw_input("用户输入:")
s_li = s.split()
words_dict = {}
for item in s_li:
    if item not in words_dict:
        words_dict[item] = 1
    else:
        words_dict[item] += 1
print (words_dict)