如何索引列表中的重复项？

def find_duplicates(lst):
    seen = {}
    duplicates = {}
    for index, item in enumerate(lst):
        if item not in seen:
            seen[item] = index
        else:
            if item not in duplicates:
                duplicates[item] = [seen[item]]
            duplicates[item].append(index)
    return {item: indices for item, indices in duplicates.items() if len(indices) > 1}

# 示例
lst = [1, 2, 3, 2, 4, 3, 5, 6, 5]
print(find_duplicates(lst))

{2: [1, 3], 3: [2, 5], 5: [6, 8]}

def find_duplicates(lst):
    seen = set()
    duplicates = {item: [] for item in lst if item in seen or seen.add(item)}
    for item in duplicates:
        duplicates[item] = [i for i, x in enumerate(lst) if x == item]
    return {k: v for k, v in duplicates.items() if len(v) > 1}

# 示例
lst = [1, 2, 3, 2, 4, 3, 5, 6, 5]
print(find_duplicates(lst))

{2: [1, 3], 3: [2, 5], 5: [6, 8]}

from collections import Counter

def find_duplicates(lst):
    counts = Counter(lst)
    duplicates = {item: indices for item, count in counts.items() if count > 1 
                  for indices in [i for i, x in enumerate(lst) if x == item]}
    return duplicates

# 示例
lst = [1, 2, 3, 2, 4, 3, 5, 6, 5]
print(find_duplicates(lst))

{2: [1, 3], 3: [2, 5], 5: [6, 8]}