diff --git a/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num1297.java b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num1297.java
new file mode 100644
index 0000000..37edbf2
--- /dev/null
+++ b/src/main/java/com/cool/ling_cha_mount/sliding_windows/Num1297.java
@@ -0,0 +1,59 @@
+package com.cool.ling_cha_mount.sliding_windows;
+
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/10/12/17:17
+ * @Description: 1297. 子串的最大出现次数
+ * Level 7
+ * Hard 2
+ * Score 1748
+ */
+public class Num1297 {
+
+    public int maxFreq(String s, int maxLetters, int minSize, int maxSize) {
+        Map<String, Integer> map = new HashMap<>();
+        int[] count = new int[26];
+        char[] chars = s.toCharArray();
+        int num = 0;
+        for (int i = 0; i < minSize; i++) {
+            if (++count[chars[i] - 'a'] == 1) {
+                num++;
+            }
+        }
+        if (num <= maxLetters) {
+            String str = s.substring(0, minSize);
+            map.put(str, 1);
+        }
+        for (int i = minSize; i < chars.length; i++) {
+            char left = chars[i - minSize];
+            char right = chars[i];
+            if (--count[left - 'a'] == 0) {
+                num--;
+            }
+            if (++count[right - 'a'] == 1) {
+                num++;
+            }
+            if (num <= maxLetters) {
+                String str = s.substring(i - minSize + 1, i + 1);
+                map.put(str, map.getOrDefault(str, 0) + 1);
+            }
+        }
+        int res = 0;
+        for (Map.Entry<String, Integer> entry : map.entrySet()) {
+            res = Math.max(res, entry.getValue());
+        }
+        return res;
+    }
+
+    @Test
+    public void test() {
+        maxFreq("aababcaab", 2, 3, 4);
+    }
+}