如何识别字符串中元素的第N次重复？

def find_nth_duplicate(string, N):
    char_count = {}
    for char in string:
        if char in char_count:
            char_count[char] += 1
        else:
            char_count[char] = 1
    
    for char in string:
        if char_count[char] == N:
            return char
    
    return None  # 没有找到第N次重复的元素

# 示例用法
string = "abracadabra"
N = 2
result = find_nth_duplicate(string, N)
print(f"The {N}th duplicate in the string is: {result}")