diff --git a/Problem1.java b/Problem1.java
index e69de29b..212734e4 100644
--- a/Problem1.java
+++ b/Problem1.java
@@ -0,0 +1,15 @@
+class Solution {
+    public int[] twoSum(int[] nums, int target) {
+        int val; 
+        HashMap<Integer,Integer> map = new HashMap<>();
+        for (int i =0;i<nums.length;i++){
+            val= target - nums[i];
+            if(map.containsKey(val)){
+                return new int[]{i,map.get(val)};
+            }
+            map.put(nums[i],i);
+
+        }
+        return new int[]{-1};
+    }
+}
\ No newline at end of file
diff --git a/Problem2.java b/Problem2.java
index e69de29b..dc766b2a 100644
--- a/Problem2.java
+++ b/Problem2.java
@@ -0,0 +1,25 @@
+class Solution {
+    public int knapsack(int W, int[] val, int[] weight) {
+        int n = val.length;
+
+        int[][] dp = new int[n + 1][W + 1];
+
+        for (int i = 1; i <= n; i++) {
+            for (int j = 0; j <= W; j++) {
+
+                // not choose
+                dp[i][j] = dp[i - 1][j];
+
+                // choose
+                if (weight[i - 1] <= j) {
+                    dp[i][j] = Math.max(
+                        dp[i][j],
+                        val[i - 1] + dp[i - 1][j - weight[i - 1]]
+                    );
+                }
+            }
+        }
+
+        return dp[n][W];
+    }
+}
\ No newline at end of file