diff --git a/src/main/java/com/dota/dp/_2140/Solution.java b/src/main/java/com/dota/dp/_2140/Solution.java
new file mode 100644
index 0000000..f7709b8
--- /dev/null
+++ b/src/main/java/com/dota/dp/_2140/Solution.java
@@ -0,0 +1,13 @@
+package com.dota.dp._2140;
+
+class Solution {
+	public long mostPoints(int[][] questions) {
+		int n = questions.length;
+		var dp = new long[n + 1];
+		for (int i = n - 1; i >= 0; i--) {
+			int j = Math.min(n, i+questions[i][1]+1);
+			dp[i] = Math.max(dp[i+1], dp[j] + questions[i][0]);
+		}
+		return dp[0];
+	}
+}
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diff --git a/src/main/java/com/dota/slidingWindow/_2156/Solution.java b/src/main/java/com/dota/slidingWindow/_2156/Solution.java
new file mode 100644
index 0000000..e656848
--- /dev/null
+++ b/src/main/java/com/dota/slidingWindow/_2156/Solution.java
@@ -0,0 +1,25 @@
+package com.dota.slidingWindow._2156;
+
+class Solution {
+	public String subStrHash(String s, int power, int modulo, int k, int hashValue) {
+		long sum = 0;
+		int n = s.length();
+		int pk = 1;
+		for (int i = n - k; i < n; i++) {
+			sum = (sum + pk * (s.charAt(i) & 31)) % modulo;
+			pk = pk * power % modulo;
+		}
+
+		if (sum == hashValue) {
+			return s.substring(n - k, n);
+		}
+
+		for (int i = n - k - 1; i >= 0; i--) {
+			sum = (sum * power + s.charAt(i) & 31 - (long) pk * (s.charAt(i+k)&31) %modulo + modulo ) % modulo;
+			if (sum == hashValue) {
+				return s.substring(i, i + k);
+			}
+		}
+		return null;
+	}
+}
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diff --git a/src/main/java/com/dota/slidingWindow/_2953/Solution.java b/src/main/java/com/dota/slidingWindow/_2953/Solution.java
new file mode 100644
index 0000000..88194e3
--- /dev/null
+++ b/src/main/java/com/dota/slidingWindow/_2953/Solution.java
@@ -0,0 +1,75 @@
+package com.dota.slidingWindow._2953;
+
+import java.util.Arrays;
+
+class Solution {
+	public static void main(String[] args) {
+		int t = new Solution().countCompleteSubstrings("jjjqq",1);
+		System.out.println(t);
+	}
+	public int countCompleteSubstrings(String word, int k) {
+		int sum = 0;
+		var book = new int[word.length()];
+		Arrays.fill(book, 100);
+		for (int j = 1; j < word.length(); j++) {
+			if (Math.abs(word.charAt(j) - word.charAt(j - 1)) <= 2) {
+				book[j] = 1;
+			}
+		}
+
+		for (int i = k; i <= word.length(); i += k) {
+			var dp = new int[26];
+			int cnt = 0;
+			for (int j = 0; j < i; j++) {
+				dp[word.charAt(j) - 'a']++;
+				if (j != 0) {
+					cnt += book[j];
+				}
+			}
+
+			var flag = true;
+			for (int j = 0; j < 26; j++) {
+				if (dp[j] != 0 && dp[j] != k) {
+					flag = false;
+					break;
+				}
+			}
+
+			if (flag && cnt == (i - 1)) {
+				sum++;
+			}
+
+			int l = 0;
+			for (int j = i; j < word.length(); j++) {
+				dp[word.charAt(l) - 'a']--;
+				l++;
+				cnt -= book[l];
+				dp[word.charAt(j) - 'a']++;
+				cnt += book[j];
+				flag = true;
+				for (int jj = 0; jj < 26; jj++) {
+					if (dp[jj] != 0 && dp[jj] != k) {
+						flag = false;
+						break;
+					}
+				}
+
+				if (flag && cnt == i-1 ) {
+					sum++;
+				}
+			}
+		}
+		return sum;
+	}
+
+	public int percentageLetter(String s, char letter) {
+		int cnt = 0;
+		for (char c : s.toCharArray()) {
+			if (c==letter) {
+				cnt++;
+			}
+		}
+
+		return cnt*100/s.length();
+	}
+}
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