Time: 826 ms (55.33%), Space: 18.6 MB (63.90%) - LeetHub

Author: mrprashantkumar

0712-minimum-ascii-delete-sum-for-two-strings/0712-minimum-ascii-delete-sum-for-two-strings.py

@@ -1,23 +1,42 @@
 class Solution:
     def minimumDeleteSum(self, s1: str, s2: str) -> int:
-        def helper(i, j):
-            if i==n:
-                return sum(ord(s2[k]) for k in range(j, m))
-            if j==m:
-                return sum(ord(s1[k]) for k in range(i, n))
+        n, m = len(s1), len(s2)
+        dp = [[0]*(m+1) for _ in range(n+1)]
+
+        for i in range(n):
+            dp[i][m] = sum(ord(s1[k]) for k in range(i, n))
+        for j in range(m):
+            dp[n][j] = sum(ord(s2[k]) for k in range(j, m))
+        for i in range(n-1, -1, -1):
+            for j in range(m-1, -1, -1):
+                if s1[i] == s2[j]:
+                    dp[i][j] = dp[i+1][j+1]
+                else:
+                    rems1 = ord(s1[i])+dp[i+1][j]
+                    rems2 = ord(s2[j])+dp[i][j+1]
+                    dp[i][j] = min(rems1, rems2)
+        return dp[0][0]
+        
+        
+        
+#         def helper(i, j):
+#             if i==n:
+#                 return sum(ord(s2[k]) for k in range(j, m))
+#             if j==m:
+#                 return sum(ord(s1[k]) for k in range(i, n))
 
-            if dp[i][j] != -1:
-                return dp[i][j]
+#             if dp[i][j] != -1:
+#                 return dp[i][j]
 
-            if s1[i] == s2[j]:
-                dp[i][j] = helper(i+1, j+1)
-                return dp[i][j]
-            else:
-                rems1 = ord(s1[i])+helper(i+1, j)
-                rems2 = ord(s2[j])+helper(i, j+1)
-                dp[i][j] = min(rems1, rems2)
-                return dp[i][j]
+#             if s1[i] == s2[j]:
+#                 dp[i][j] = helper(i+1, j+1)
+#                 return dp[i][j]
+#             else:
+#                 rems1 = ord(s1[i])+helper(i+1, j)
+#                 rems2 = ord(s2[j])+helper(i, j+1)
+#                 dp[i][j] = min(rems1, rems2)
+#                 return dp[i][j]
 
-        n, m = len(s1), len(s2)
-        dp = [[-1]*m for _ in range(n)]
-        return helper(0, 0)
+        # n, m = len(s1), len(s2)
+        # dp = [[-1]*m for _ in range(n)]
+#         return helper(0, 0)