diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 460073b..5a24abe 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -182,4 +182,5 @@ mod p153_find_minimum_in_rotated_sorted_array;
 mod p215_kth_largest_element_in_an_array;
 mod p502_ipo;
 mod p373_find_k_pairs_with_smallest_sums;
-mod p295_find_median_from_data_stream;
\ No newline at end of file
+mod p295_find_median_from_data_stream;
+mod p67_add_binary;
\ No newline at end of file
diff --git a/src/problem/p67_add_binary.rs b/src/problem/p67_add_binary.rs
new file mode 100644
index 0000000..a2901c8
--- /dev/null
+++ b/src/problem/p67_add_binary.rs
@@ -0,0 +1,60 @@
+/**
+ * [67] Add Binary
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn add_binary(a: String, b: String) -> String {
+        let a: Vec<u32> = a.chars().rev().map(|c| c.to_digit(10).unwrap()).collect();
+        let b: Vec<u32> = b.chars().rev().map(|c| c.to_digit(10).unwrap()).collect();
+
+        let mut result: Vec<u32> = Vec::with_capacity(a.len().max(b.len()) + 2);
+
+        let mut overflow = 0;
+        for i in 0..a.len().max(b.len()) {
+            let mut bit = overflow;
+            
+            if i < a.len() {
+                bit += a[i];
+            }
+            if i < b.len() {
+                bit += b[i];
+            }
+            
+            match bit { 
+                3 => {result.push(1); overflow = 1},
+                2 => {result.push(0); overflow = 1},
+                1 => {result.push(1); overflow = 0},
+                0 => {result.push(0); overflow = 0},
+                _ => {}
+            }
+        }
+        
+        if overflow != 0 {
+            result.push(overflow);
+        }
+        
+        if result.len() == 0 {
+            result.push(0);
+        }
+
+        result.iter().rev().map(|i| i.to_string()).collect()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_67() {
+        assert_eq!("100".to_owned(), Solution::add_binary("11".to_owned(), "1".to_owned()));
+        assert_eq!("10101".to_owned(), Solution::add_binary("1010".to_owned(), "1011".to_owned()));
+        assert_eq!("110110".to_owned(), Solution::add_binary("100".to_owned(), "110010".to_owned()));
+    }
+}