diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 002ed57..64d6797 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -122,4 +122,5 @@ mod p54_spiral_matrix;
 mod p48_rotate_image;
 mod p73_set_matrix_zeroes;
 mod p289_game_of_life;
-mod p383_ransom_note;
\ No newline at end of file
+mod p383_ransom_note;
+mod p205_isomorphic_strings;
\ No newline at end of file
diff --git a/src/problem/p205_isomorphic_strings.rs b/src/problem/p205_isomorphic_strings.rs
new file mode 100644
index 0000000..e72e657
--- /dev/null
+++ b/src/problem/p205_isomorphic_strings.rs
@@ -0,0 +1,42 @@
+/**
+ * [205] Isomorphic Strings
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn is_isomorphic(s: String, t: String) -> bool {
+        let mut inverse_map = HashMap::with_capacity(s.len());
+        let mut reverse_map = HashMap::with_capacity(t.len());
+
+        for (c1, c2) in s.chars().zip(t.chars()) {
+            let entry = inverse_map.entry(c1).or_insert(c2);
+
+            if *entry != c2 {
+                return false;
+            }
+
+            let entry = reverse_map.entry(c2).or_insert(c1);
+
+            if *entry != c1 {
+                return false;
+            }
+        }
+
+        true
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_205() {
+    }
+}