diff --git a/solution/3500-3599/3595.Once Twice/README.md b/solution/3500-3599/3595.Once Twice/README.md
new file mode 100644
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+---
+comments: true
+difficulty: 中等
+edit_url: https://github.com/doocs/leetcode/edit/main/solution/3500-3599/3595.Once%20Twice/README.md
+---
+
+
+
+# [3595. 一次或两次 🔒](https://leetcode.cn/problems/once-twice)
+
+[English Version](/solution/3500-3599/3595.Once%20Twice/README_EN.md)
+
+## 题目描述
+
+
+
+给定一个整数数组 nums。在这个数组中：
+
+
+ -
+
有一个元素出现了 恰好 1 次。
+
+ -
+
有一个元素出现了 恰好 2 次。
+
+ -
+
其它所有元素都出现了 恰好 3 次。
+
+
+
+返回一个长度为 2 的整数数组，其中第一个元素是只出现 1 次 的那个元素，第二个元素是只出现 2 次 的那个元素。
+
+你的解决方案必须在 O(n) 时间 与 O(1) 空间中运行。
+
+
+
+示例 1：
+
+
+
输入：nums = [2,2,3,2,5,5,5,7,7]
+
+
输出：[3,7]
+
+
解释：
+
+
元素 3 出现了 1 次，元素 7 出现了 2 次。其余所有元素都出现了 3 次。
+
示例 2：
+
+
+
输入：nums = [4,4,6,4,9,9,9,6,8]
+
+
输出：[8,6]
+
+
解释：
+
+
元素 8 出现了 1 次，元素 6 出现了 2 次。其余所有元素都出现了 3 次。
+
+
+提示：
+
+
+ 3 <= nums.length <= 105-231 <= nums[i] <= 231 - 1nums.length 是 3 的倍数。- 恰好有一个元素出现 1 次，一个元素出现 2 次，其余所有元素都出现了 3 次。
+
+
+
+
+## 解法
+
+
+
+### 方法一
+
+
+
+#### Python3
+
+```python
+
+```
+
+#### Java
+
+```java
+
+```
+
+#### C++
+
+```cpp
+
+```
+
+#### Go
+
+```go
+
+```
+
+
+
+
+
+
diff --git a/solution/3500-3599/3595.Once Twice/README_EN.md b/solution/3500-3599/3595.Once Twice/README_EN.md
new file mode 100644
index 0000000000000..1231be24e6089
--- /dev/null
+++ b/solution/3500-3599/3595.Once Twice/README_EN.md
@@ -0,0 +1,108 @@
+---
+comments: true
+difficulty: Medium
+edit_url: https://github.com/doocs/leetcode/edit/main/solution/3500-3599/3595.Once%20Twice/README_EN.md
+---
+
+
+
+# [3595. Once Twice 🔒](https://leetcode.com/problems/once-twice)
+
+[中文文档](/solution/3500-3599/3595.Once%20Twice/README.md)
+
+## Description
+
+
+
+You are given an integer array nums. In this array:
+
+
+ -
+
Exactly one element appears once.
+
+ -
+
Exactly one element appears twice.
+
+ -
+
All other elements appear exactly three times.
+
+
+
+Return an integer array of length 2, where the first element is the one that appears once, and the second is the one that appears twice.
+
+Your solution must run in O(n) time and O(1) space.
+
+
+Example 1:
+
+
+
Input: nums = [2,2,3,2,5,5,5,7,7]
+
+
Output: [3,7]
+
+
Explanation:
+
+
The element 3 appears once, and the element 7 appears twice. The remaining elements each appear three times.
+
Example 2:
+
+
+
Input: nums = [4,4,6,4,9,9,9,6,8]
+
+
Output: [8,6]
+
+
Explanation:
+
+
The element 8 appears once, and the element 6 appears twice. The remaining elements each appear three times.
+
+Constraints:
+
+
+ 3 <= nums.length <= 105-231 <= nums[i] <= 231 - 1nums.length is a multiple of 3.- Exactly one element appears once, one element appears twice, and all other elements appear three times.
+
+
+
+
+## Solutions
+
+
+
+### Solution 1
+
+
+
+#### Python3
+
+```python
+
+```
+
+#### Java
+
+```java
+
+```
+
+#### C++
+
+```cpp
+
+```
+
+#### Go
+
+```go
+
+```
+
+
+
+
+
+
diff --git a/solution/README.md b/solution/README.md
index a424a1f14980e..ae9226b1539b9 100644
--- a/solution/README.md
+++ b/solution/README.md
@@ -3605,6 +3605,7 @@
| 3592 | [硬币面值还原](/solution/3500-3599/3592.Inverse%20Coin%20Change/README.md) | | 中等 | 第 455 场周赛 |
| 3593 | [使叶子路径成本相等的最小增量](/solution/3500-3599/3593.Minimum%20Increments%20to%20Equalize%20Leaf%20Paths/README.md) | | 中等 | 第 455 场周赛 |
| 3594 | [所有人渡河所需的最短时间](/solution/3500-3599/3594.Minimum%20Time%20to%20Transport%20All%20Individuals/README.md) | | 困难 | 第 455 场周赛 |
+| 3595 | [一次或两次](/solution/3500-3599/3595.Once%20Twice/README.md) | | 中等 | 🔒 |
## 版权
diff --git a/solution/README_EN.md b/solution/README_EN.md
index e1114669afb1c..92e75f34952de 100644
--- a/solution/README_EN.md
+++ b/solution/README_EN.md
@@ -3603,6 +3603,7 @@ Press Control + F(or Command + F on
| 3592 | [Inverse Coin Change](/solution/3500-3599/3592.Inverse%20Coin%20Change/README_EN.md) | | Medium | Weekly Contest 455 |
| 3593 | [Minimum Increments to Equalize Leaf Paths](/solution/3500-3599/3593.Minimum%20Increments%20to%20Equalize%20Leaf%20Paths/README_EN.md) | | Medium | Weekly Contest 455 |
| 3594 | [Minimum Time to Transport All Individuals](/solution/3500-3599/3594.Minimum%20Time%20to%20Transport%20All%20Individuals/README_EN.md) | | Hard | Weekly Contest 455 |
+| 3595 | [Once Twice](/solution/3500-3599/3595.Once%20Twice/README_EN.md) | | Medium | 🔒 |
## Copyright