diff --git a/src/双指针遍历/q3_无重复字符的最长子串/Solution.py b/src/双指针遍历/q3_无重复字符的最长子串/Solution.py
new file mode 100644
index 0000000..c79fb71
--- /dev/null
+++ b/src/双指针遍历/q3_无重复字符的最长子串/Solution.py
@@ -0,0 +1,19 @@
+class Solution:
+    def lengthOfLongestSubstring(self, s: str) -> int:
+        if len(s)<=1:
+            return len(s)
+        res = []
+        i = 0
+        j = 0
+        ans = 1
+        n = len(s)
+        while i<n and j<n:
+            if s[j] not in res:
+                res.append(s[j])
+                j+=1
+                ans = max(ans,j-i)
+            else:
+                res.remove(s[i])
+                i+=1
+        return ans
+