Completed CompCoding2

Solutions.py

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+# Problem 1:  https://leetcode.com/problems/two-sum/
+# Time complexity : O(n)
+# Space Complexity : O(1)
+
+class Solution:
+    def __init__():
+
+    def twoSum(self,nums,target):
+        hashmap = {}
+        for i in range(0,len(nums)):
+            diff = target - nums[i]
+            if diff in hashmap:
+                return [i,hashmap[diff]]
+            hashmap[nums[i]] = i
+
+
+# Problem 2: https://www.geeksforgeeks.org/0-1-knapsack-problem-dp-10/
+# Time complexity : O(mn)
+# Space Complexity : O(mn)
+## 0-1 knapsack problem was asked during the interview, I followed the same pattern taught in class
+## Tried to identify base case , choose and not choose conditions
+## called the helper directly without memo to show the iterative approach and then included memo for dp sol
+## if choosing  a weight, the total available weight reduces index increases and memo is passed
+## if not choose just the index increases
+## return the max of both
+
+class Solution:
+    def __init__():
+
+    def helper(W,idx,memo):
+        ## base case
+        if W <= 0 or idx>=len(wt):
+            return 0
+        if memo[W][idx] != -1:
+            return memo[W][idx]
+        ## choose a weight
+        case1 =0
+        if wt[idx] <=W:
+            case1 = val[idx] + helper(W-wt[idx], idx+1,memo)
+
+        ## dont choose
+        case2 = helper(W, idx+1,memo)
+        res = max(case1,case2)
+        memo[W][idx] = res
+        return res
+    memo = [[-1] * len(wt) for _ in range(W + 1)]
+    res = helper(W,0,memo)
+    return res