dp3

delete-and-earn.py

@@ -0,0 +1,17 @@
+# O(n) time, O(n) space
+class Solution:
+    def deleteAndEarn(self, nums: List[int]) -> int:
+
+        if not nums:
+            return 0
+
+        maxVal = max(nums)
+        t = [0]*(maxVal+1)
+
+        for num in nums:
+            t[num]+=num
+
+        for i in range(2,len(t)):
+            t[i]=max(t[i-1],t[i]+t[i-2])
+
+        return t[-1]

min-falling-path-sum.py

@@ -0,0 +1,25 @@
+# time O(n*n), space O(n*n)
+class Solution:
+    def minFallingPathSum(self, matrix: List[List[int]]) -> int:
+        n=len(matrix)
+        dp = [[0] * n for i in range(n)]
+        for i in range(n):
+            dp[0][i]=matrix[0][i]
+
+        for i in range(1,n):
+            for j in range(n):
+                # first col - 2 val compare
+                if j==0:
+                    dp[i][j]=matrix[i][j]+min(dp[i-1][j],dp[i-1][j+1])
+                # last col - 2 val compare
+                elif j == n-1:
+                    dp[i][j]=matrix[i][j]+min(dp[i-1][j],dp[i-1][j-1])
+                # middle - compare all 3
+                else:
+                    dp[i][j]=matrix[i][j]+min(dp[i-1][j-1],dp[i-1][j],dp[i-1][j+1])
+
+        # return the min of the last row
+        res = dp[n-1][0]
+        for i in range(n):
+            res= min(dp[n-1][i],res)
+        return res