Completed S30 DP-1

coinchange.py

@@ -0,0 +1,20 @@
+from typing import List
+class Solution:
+    def coinChange(self, coins: List[int], amount: int) -> int:
+        dp = [amount + 1] * (amount + 1)
+        dp[0] = 0
+        # dp = [0,1,1,2,2,1,2,2,3,3,2,3]
+
+        for a in range(1, amount + 1):
+            for c in coins:
+                if a - c >= 0:
+                    dp[a] = min(dp[a], 1 + dp[a - c])
+
+        if dp[-1] != (amount + 1):
+            return dp[-1]
+        return -1
+
+   # A = amount
+   # N = number of coins
+    # TC = O(A+N)
+    # SC = O(A) DP array has amount+1 number of entries

houserobber.py

@@ -0,0 +1,21 @@
+class Solution:
+    def rob(self, nums):
+        n = len(nums)
+        if n == 1:
+            return nums[0]
+        dp = [0] * n
+        dp[0] = nums[0]
+        dp[1] = max(nums[0], nums[1])
+
+        prev2 = 0
+        prev1 = 0
+
+        for money in nums:
+            curr = max(prev1, prev2 + money)
+            prev2 = prev1
+            prev1 = curr
+
+        return prev1
+
+    # TC O(n)
+    # SC O(1) # if you use DP it's O(n) This is space optimized pointers version