diff --git a/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2730.java b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2730.java
new file mode 100644
index 0000000..87b3342
--- /dev/null
+++ b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num2730.java
@@ -0,0 +1,31 @@
+package com.cool.ling_cha_mount.sliding_windows;
+
+import org.junit.Test;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024 /10/19/19:07
+ * @Description: 2730. 找到最长的半重复子字符串
+ * Score 1502
+ */
+public class Num2730 {
+    public int longestSemiRepetitiveSubstring(String s) {
+        char[] chars = s.toCharArray();
+        int ans = 1, left = 0, same = 0, n = chars.length;
+        for (int right = 1; right < n; right++) {
+            if (chars[right] == chars[right - 1] && ++same > 1) {
+                for (left++; chars[left] != chars[left - 1]; left++) ;
+                same = 1;
+            }
+            ans = Math.max(ans, right - left + 1);
+        }
+        return ans;
+    }
+
+    @Test
+    public void test() {
+        longestSemiRepetitiveSubstring("52233");
+    }
+}