diff --git a/src/main/java/com/dota/slidingWindow/_1297/Solution.java b/src/main/java/com/dota/slidingWindow/_1297/Solution.java
new file mode 100644
index 0000000..609f1ec
--- /dev/null
+++ b/src/main/java/com/dota/slidingWindow/_1297/Solution.java
@@ -0,0 +1,47 @@
+package com.dota.slidingWindow._1297;
+
+import java.util.HashMap;
+
+class Solution {
+	public int maxFreq(String s, int maxLetters, int minSize, int maxSize) {
+		int max = 0;
+		var dp = new int[26];
+
+		int cnt = 0;//字母数
+		var map = new HashMap<String, Integer>();//出现数量
+		for (int i = 0; i < minSize; i++) {
+			int t = s.charAt(i) - 'a';
+			if (dp[t] == 0) {
+				cnt++;
+			}
+			dp[t]++;
+		}
+		if (cnt<=maxLetters) {
+			map.put(s.substring(0, minSize), 1);
+			max = 1;
+		}
+
+		for (int i = minSize; i < s.length(); i++) {
+			int t = s.charAt(i-minSize) - 'a';
+			if (dp[t] == 1) {
+				cnt--;
+			}
+			dp[t]--;
+
+			t = s.charAt(i) - 'a';
+			if (dp[t] == 0) {
+				cnt++;
+			}
+			dp[t]++;
+
+			if (cnt<=maxLetters) {
+				var tmp = s.substring(i-minSize, i+1);
+				map.put(tmp, map.getOrDefault(tmp, 0)+1);
+				max = Math.max(max, map.get(tmp));
+			}
+		}
+
+
+		return max;
+	}
+}
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