diff --git a/knapsack.py b/knapsack.py
new file mode 100644
index 00000000..15538f2b
--- /dev/null
+++ b/knapsack.py
@@ -0,0 +1,28 @@
+"""
+time - o(n)
+space - o(n)
+we create a 2d array where inner array size = capacity and number of arrays is equal to the number of weights
+we iterate each array which represents a weight in the weights array and each inner array cell is the current capacity of the sack
+if the current capacity is lesser than the weight we take the previous weight's value at the same capacity, if not we take max between
+previous weight's value at that capacity and capacity - weight's value plus current capacity's value
+(what value we'll currently have if we choose the weight along with the previous choice)
+"""
+
+
+def knapsack(weights, values, capacity):
+    n = len(weights)
+    dp = [[0 for _ in range(capacity + 1)] for _ in range(n + 1)]
+
+    for i in range(1, n + 1):
+        for w in range(capacity + 1):
+            if weights[i - 1] <= w:
+                # Include or exclude current item
+                dp[i][w] = max(
+                    dp[i - 1][w],  # don't choose
+                    dp[i - 1][w - weights[i - 1]] + values[i - 1],  # choose
+                )
+            else:
+                # Cannot include current item
+                dp[i][w] = dp[i - 1][w]
+
+    return dp[n][capacity]
diff --git a/two_sum.py b/two_sum.py
new file mode 100644
index 00000000..92e8dbda
--- /dev/null
+++ b/two_sum.py
@@ -0,0 +1,18 @@
+"""
+space = o(n)
+time = o(n)
+store numbers in a dictionary and if we have it's complement as seen before
+we return the two nunmbers
+"""
+
+from typing import List
+
+
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        seen = {}
+        for i in range(len(nums)):
+            complement = target - nums[i]
+            if complement in seen:
+                return [i, seen[complement]]
+            seen[nums[i]] = i