xxxxxxxxxx
def find_disappeared_numbers(nums):
for num in nums:
index = abs(num) - 1
nums[index] = -abs(nums[index])
return [i + 1 for i, num in enumerate(nums) if num > 0]
# Example usage
arr = [4, 3, 2, 7, 8, 2, 3, 1]
disappeared = find_disappeared_numbers(arr)
print(disappeared)