LeetCode 712 Minimum ASCII Delete Sum for Two Strings - Walkthrough

Find the lowest ASCII sum of deleted characters to make strings equal. This is weighted LCS. Alternative view: find the largest ASCII sum of kept characters (the LCS), then answer = total sum - 2 * kept sum.

Trace on $s_1 = \text{"sea"}$, $s_2 = \text{"eat"}$. Common subsequence "ea" has sum $101 + 97 = 198$. Delete "s" (115) and "t" (116). Total: $231$. DP: $dp[i][j]$ = max ASCII sum of common subsequence. When chars match, add ASCII value. Time: $O(mn)$, Space: $O(mn)$.