diff --git a/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num125.java b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num125.java
new file mode 100644
index 0000000..8d6a8c0
--- /dev/null
+++ b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num125.java
@@ -0,0 +1,29 @@
+package com.cool.ling_cha_mount.sliding_windows;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/11/03/19:06
+ * @Description: 125. 验证回文串
+ */
+public class Num125 {
+    public boolean isPalindrome(String s) {
+        StringBuilder stringBuilder=new StringBuilder();
+        for(char c:s.toCharArray()){
+            if(Character.isLetterOrDigit(c)){
+                stringBuilder.append(c);
+            }
+        }
+        String s1 = new String(stringBuilder);
+        s1 = s1.toLowerCase();
+        int right=s1.length()-1;
+        int left=0;
+        while(left<right){
+            if(s1.charAt(left++)!=s1.charAt(right--)){
+                return false;
+            }
+        }
+        return true;
+    }
+}