diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index ebe03b5..2733115 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -185,4 +185,5 @@ mod p373_find_k_pairs_with_smallest_sums;
 mod p295_find_median_from_data_stream;
 mod p67_add_binary;
 mod p190_reverse_bits;
-mod p191_number_of_1_bits;
\ No newline at end of file
+mod p191_number_of_1_bits;
+mod p136_single_number;
\ No newline at end of file
diff --git a/src/problem/p136_single_number.rs b/src/problem/p136_single_number.rs
new file mode 100644
index 0000000..5c1e84c
--- /dev/null
+++ b/src/problem/p136_single_number.rs
@@ -0,0 +1,32 @@
+/**
+ * [136] Single Number
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn single_number(nums: Vec<i32>) -> i32 {
+        let mut result = 0;
+
+        for i in nums {
+            result ^= i;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_136() {
+        assert_eq!(1, Solution::single_number(vec![1, 2, 2]));
+        assert_eq!(1, Solution::single_number(vec![1]));
+    }
+}