电话号码的字母组合（python）

问题描述：

依旧是组合问题，不过之前是一个集合，这里是多个集合。

用一个哈希表存储数字和字母的对应关系。

mp={"0":"","1":"","2":"abc","3":"def","4":"ghi","5":"jkl","6":"mno","7":"pqrs","8":"tuv","9":"wxyz"}

#电话号码字母组合
import sys
sys.setrecursionlimit(1000000)
def f(s):   #:"23"
    res=[]
    path=[]
    n=len(s)
    mp={"0":"","1":"","2":"abc","3":"def","4":"ghi","5":"jkl","6":"mno","7":"pqrs","8":"tuv","9":"wxyz"}
    def dfs(idx):   #遍历到s的第几个数字
        if idx==n:  #超过了数字最大索引，就收集结果
            res.append("".join(path[:]))
            return
        for i in range(len(mp[s[idx]])):
            ch=mp[s[idx]][i]
            path.append(ch)
            dfs(idx+1)
            path.pop()
    dfs(0)
    print(res)
    return
def main():
    s=input().strip()
    f(s)
if __name__=="__main__":
    main()