diff --git a/longest-substring-without-repeating-characters/sol.rs b/longest-substring-without-repeating-characters/sol.rs
new file mode 100644
index 0000000..0570ae1
--- /dev/null
+++ b/longest-substring-without-repeating-characters/sol.rs
@@ -0,0 +1,18 @@
+use std::collections::HashSet;
+
+impl Solution {
+    pub fn length_of_longest_substring(s: String) -> i32 {
+        let bytes = s.as_bytes();
+        let mut exists = HashSet::new();
+        let mut max = 0;
+        let mut p1 = 0;
+        for p2 in 0..s.len() {
+            while !exists.insert(bytes[p2]) {
+                exists.remove(&bytes[p1]);
+                p1 += 1;
+            }
+            max = max.max(exists.len());
+        }
+        max as i32
+    }
+}
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