枚举给定列表中所有元素的多个集合，其总和为给定的数字

def find_subsets_with_sum(nums, target):
    def backtrack(start, target, path):
        if target == 0:
            result.append(path.copy())
            return
        if target < 0:
            return
        for i in range(start, len(nums)):
            path.append(nums[i])
            backtrack(i + 1, target - nums[i], path)
            path.pop()

    result = []
    nums.sort()  # Sorting helps in avoiding duplicates and improves efficiency
    backtrack(0, target, [])
    return result

# 示例使用
nums = [2, 4, 6, 8]
target = 8
print(find_subsets_with_sum(nums, target))