diff --git a/#442/java/hashmap/.DS_Store b/#442/java/hashmap/.DS_Store
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diff --git a/#442/java/hashmap/Solution.java b/#442/java/hashmap/Solution.java
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+package com.jagjit.Hactoberfest;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+
+/**
+ * https://leetcode.com/problems/find-all-duplicates-in-an-array/
+ * runtime beats 9.32% of Java submissions
+ * memory usage beats 36.11% of Java submissions
+ */
+
+
+public class FindDuplicates {
+
+	// function that return the value
+	private static List<Integer> findDuplicates(int[] nums) {
+
+		List<Integer> result = new ArrayList<Integer>();
+
+		// initialising the hashmap
+		int count = 0;
+		Map<Integer, Integer> map = new HashMap<Integer, Integer>();
+		
+		//iterates through every element 
+		for (int i = 0; i < nums.length; i++) {
+			
+			//if map contains duplicate value then add to result list
+			if (map.containsKey(nums[i])) {
+				result.add(nums[i]);
+			}
+			//putting the value in the map
+			map.put(nums[i], count++);
+		}
+		
+		//return the final list
+		return result;
+
+	}
+
+	public static void main(String[] args) {
+
+		// allocating memory for 5 integers.
+		int[] nums = new int[8];
+
+		// initialize the first elements of the array
+		nums[0] = 4;
+		nums[1] = 3;
+		nums[2] = 2;
+		nums[3] = 7;
+		nums[4] = 8;
+		nums[5] = 2;
+		nums[6] = 3;
+		nums[7] = 1;
+
+		List<Integer> result = findDuplicates(nums);
+
+		for (Integer i : result) {
+			
+			//print the value of duplicates value
+			System.out.print(i + " ");
+
+		}
+
+	}
+
+}
diff --git a/#70/java/dynamic_programming/Solution.java b/#70/java/dynamic_programming/Solution.java
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+package com.jagjit.Hactoberfest;
+
+/**
+ * https://leetcode.com/problems/climbing-stairs/ Runtime: 0 ms, faster than
+ * 100.00% of Java online submissions for Climbing Stairs. Memory Usage: 33.2
+ * MB, less than 5.26% of Java online submissions for Climbing Stairs.
+ */
+public class Solution {
+
+	// below the function which returns count
+	public int climbStairs(int n) {
+		int[] dp = new int[n];
+		if (n < 2) {
+			return 1;
+		}
+		dp[0] = 1;
+		dp[1] = 2;
+		for (int i = 2; i < n; i++) {
+			dp[i] = dp[i - 1] + dp[i - 2];
+		}
+		return dp[n - 1];
+	}
+
+}