diff --git a/README.md b/README.md
index 200a58a..b487f85 100644
--- a/README.md
+++ b/README.md
@@ -49,9 +49,9 @@ cargo test
 |  #  | Title           |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note| 
 |-----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------|-----|
 0136 | [Single Number](https://leetcode.com/problems/single-number/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/single-number.cpp) <br> [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/single-number.py) <br> [Rust](./kamyu104/src/single_number.rs) | _O(n)_       | _O(1)_          | Easy         |||
+0137 | [Single Number II](https://leetcode.com/problems/single-number-ii/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/single-number-ii.cpp) <br> [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/single-number-ii.py) <br> [Rust](./kamyu104/src/single_number_ii.rs) | _O(n)_ | _O(1)_          | Medium         |||
 
 <!-- 
-0137 | [Single Number II](https://leetcode.com/problems/single-number-ii/) | [C++](./C++/single-number-ii.cpp) [Python](./Python/single-number-ii.py) | _O(n)_ | _O(1)_          | Medium         |||
 0190 | [Reverse Bits](https://leetcode.com/problems/reverse-bits/)  | [C++](./C++/reverse-bits.cpp) [Python](./Python/reverse-bits.py) | _O(1)_        | _O(1)_          | Easy           |||
 0191  |[Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits/) | [C++](./C++/number-of-1-bits.cpp) [Python](./Python/number-of-1-bits.py) | _O(1)_ | _O(1)_          | Easy           |||
 0201 | [Bitwise AND of Numbers Range](https://leetcode.com/problems/bitwise-and-of-numbers-range/) | [C++](./C++/bitwise-and-of-numbers-range.cpp) [Python](./Python/bitwise-and-of-numbers-range.py) | _O(1)_ | _O(1)_ | Medium ||
diff --git a/kamyu104/src/main.rs b/kamyu104/src/main.rs
index 097acdb..e8b77be 100644
--- a/kamyu104/src/main.rs
+++ b/kamyu104/src/main.rs
@@ -1,2 +1,3 @@
-mod template;
 mod single_number;
+mod single_number_ii;
+mod template;
diff --git a/kamyu104/src/single_number_ii.rs b/kamyu104/src/single_number_ii.rs
new file mode 100644
index 0000000..530b8ca
--- /dev/null
+++ b/kamyu104/src/single_number_ii.rs
@@ -0,0 +1,71 @@
+use std::collections::HashSet;
+
+pub struct Solution1 {}
+pub struct Solution2 {}
+pub struct Solution3 {}
+pub struct Solution4 {}
+
+impl Solution1 {
+    pub fn single_number(nums: Vec<i32>) -> i32 {
+        let (mut one, mut two): (i32, i32) = (0, 0);
+        for num in nums.iter() {
+            let new_one = (!num & one) | (num & !one & !two);
+            let new_two = (!num & two) | (num & one);
+            one = new_one;
+            two = new_two;
+        }
+        one
+    }
+}
+
+impl Solution2 {
+    pub fn single_number(nums: Vec<i32>) -> i32 {
+        let (mut one, mut two, mut carry): (i32, i32, i32) = (0, 0, 0);
+        for num in nums.iter() {
+            two |= one & num;
+            one ^= num;
+            carry = one & two;
+            one &= !carry;
+            two &= !carry;
+        }
+        one
+    }
+}
+
+// https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/single-number-ii.py#L31
+// impl Solution3 {
+//     pub fn single_number(nums: Vec<i32>) -> i32 {
+//     }
+// }
+
+impl Solution4 {
+    pub fn single_number(nums: Vec<i32>) -> i32 {
+        let sum: i32 = nums.iter().sum();
+        let set_sum: i32 = nums.iter().cloned().collect::<HashSet<i32>>().iter().sum();
+        (3 * set_sum - sum) / 2
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_add() {
+        assert_eq!(Solution1::single_number(vec![2, 2, 3, 2]), 3);
+        assert_eq!(Solution1::single_number(vec![0, 1, 0, 1, 0, 1, 99]), 99);
+        assert_eq!(Solution1::single_number(vec![0, 0, 0, 1, 1, 1, 5]), 5);
+
+        assert_eq!(Solution2::single_number(vec![2, 2, 3, 2]), 3);
+        assert_eq!(Solution2::single_number(vec![0, 1, 0, 1, 0, 1, 99]), 99);
+        assert_eq!(Solution2::single_number(vec![0, 0, 0, 1, 1, 1, 5]), 5);
+
+        // assert_eq!(Solution3::single_number(vec![2,2,3,2]), 3);
+        // assert_eq!(Solution3::single_number(vec![0,1,0,1,0,1,99]), 99);
+        // assert_eq!(Solution3::single_number(vec![0, 0, 0, 1, 1, 1, 5]), 5);
+
+        assert_eq!(Solution4::single_number(vec![2, 2, 3, 2]), 3);
+        assert_eq!(Solution4::single_number(vec![0, 1, 0, 1, 0, 1, 99]), 99);
+        assert_eq!(Solution4::single_number(vec![0, 0, 0, 1, 1, 1, 5]), 5);
+    }
+}