diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index ee13a71..86cf501 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -188,4 +188,5 @@ mod p190_reverse_bits;
 mod p191_number_of_1_bits;
 mod p136_single_number;
 mod p137_single_number_ii;
-mod p201_bitwise_and_of_numbers_range;
\ No newline at end of file
+mod p201_bitwise_and_of_numbers_range;
+mod p66_plus_one;
\ No newline at end of file
diff --git a/src/problem/p66_plus_one.rs b/src/problem/p66_plus_one.rs
new file mode 100644
index 0000000..fb57d53
--- /dev/null
+++ b/src/problem/p66_plus_one.rs
@@ -0,0 +1,38 @@
+/**
+ * [66] Plus One
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn plus_one(digits: Vec<i32>) -> Vec<i32> {
+        let mut digits = digits;
+        let mut overflow = 1;
+        
+        for i in (0..digits.len()).rev() {
+            let bit = digits[i] + overflow;
+            digits[i] = bit % 10;
+            overflow = bit / 10;
+        }
+        
+        if overflow > 0 {
+            digits.insert(0, overflow);
+        }
+
+        digits
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_66() {
+        assert_eq!(vec![1, 0], Solution::plus_one(vec![9]));
+    }
+}