From 61dcce1a7601d238943d43351df3aab87f52bee6 Mon Sep 17 00:00:00 2001
From: Bauke <me@bauke.xyz>
Date: Sat, 9 Apr 2022 20:25:08 +0200
Subject: [PATCH] Solve isomorphic-strings.

---
 source/isomorphic_strings/mod.rs | 15 +++++++++++++++
 source/lib.rs                    |  1 +
 tests/isomorphic_strings.rs      | 11 +++++++++++
 3 files changed, 27 insertions(+)
 create mode 100644 source/isomorphic_strings/mod.rs
 create mode 100644 tests/isomorphic_strings.rs

diff --git a/source/isomorphic_strings/mod.rs b/source/isomorphic_strings/mod.rs
new file mode 100644
index 0000000..41599e7
--- /dev/null
+++ b/source/isomorphic_strings/mod.rs
@@ -0,0 +1,15 @@
+pub fn is_isomorphic(a: String, b: String) -> bool {
+  let mut map_a = std::collections::HashMap::new();
+  let mut map_b = std::collections::HashMap::new();
+
+  for (a, b) in a.chars().zip(b.chars()) {
+    let from_map_a = *map_a.entry(a).or_insert(b);
+    let from_map_b = *map_b.entry(b).or_insert(a);
+
+    if from_map_b != a || from_map_a != b {
+      return false;
+    }
+  }
+
+  true
+}
diff --git a/source/lib.rs b/source/lib.rs
index 1814c68..5b9f1b4 100644
--- a/source/lib.rs
+++ b/source/lib.rs
@@ -2,6 +2,7 @@ pub mod add_binary;
 pub mod excel_sheet_column_number;
 pub mod excel_sheet_column_title;
 pub mod implement_strstr;
+pub mod isomorphic_strings;
 pub mod length_of_last_word;
 pub mod longest_common_prefix;
 pub mod missing_number;
diff --git a/tests/isomorphic_strings.rs b/tests/isomorphic_strings.rs
new file mode 100644
index 0000000..9d3c4bb
--- /dev/null
+++ b/tests/isomorphic_strings.rs
@@ -0,0 +1,11 @@
+use leetcode::isomorphic_strings::is_isomorphic;
+
+use test_case::test_case;
+
+#[test_case("egg", "add", true; "valid")]
+#[test_case("foo", "bar", false; "invalid")]
+#[test_case("badc", "baba", false; "map both ways")]
+#[test_case("paper", "title", true; "different maps")]
+fn test_isomorphic_strings(a: &str, b: &str, expected: bool) {
+  assert_eq!(is_isomorphic(a.to_string(), b.to_string()), expected);
+}