我如何在python中接受用户的嵌套字典

我正在研究非确定性有限自动机（NFA）的模拟，我想让用户输入状态、字母和事务功能。对于事务功能：变量t_state用户可以像这样为每个字母输入多个状态

我使用了嵌套字典

count_State = int(input("Please enter the number of NFA states..\n"))
states=list(map(int, input("Enter the states:-").strip().split()))         # NFA state set
count_alpha = int(input("Please enter the number of alphabets used\n"))
symbols=list(map(str, input("Enter the NFA alphabets:-").strip().split()))  # NFA alphabet
t_state = {}
for i in range(count_State):
    dict_name = input("Enter the state: ")
    t_state[dict_name] = {}
    for i in range(count_alpha):
        alphabet = input("Enter the alphabet: ")
        numVals = int(input("How many transition for that alphabet?\n"))
        transiction = []
        for value in range(numVals):
            transiction.append(input("Next transition\n"))
            dict_name[alphabet] = transiction
print(t_state)

我收到了这个错误：dict_name[alphabet] = transiction TypeError: 'str' object does not support item assignment

预期输出：

t_state = {
        '1': {
            'a': ['2','4'],
            'b': ['3']
        },
        '2': {
            'a': ['5'],
            'b': ['1']
        },
        '3': {
            'a': ['5'],
            'b': ['1']
        },
        '4': {
            'a': ['1'],
            'b': ['5']
        },
        '5': {
            '#': ['2'],
            'b': ['3']
        }
    }