Challenge: Edit Distance Reconstruction

The DP gives the minimum count, but which operations? Backtrack from $dp[m][n]$. At each cell, check which case gave the minimum: diagonal (match or replace), left (insert), up (delete).

If $dp[i][j] = dp[i-1][j-1]$ and chars match: no operation. If $dp[i][j] = dp[i-1][j-1] + 1$: replace. If $dp[i][j] = dp[i-1][j] + 1$: delete from $s_1$. If $dp[i][j] = dp[i][j-1] + 1$: insert into $s_1$. When ties occur between operations, prefer the one that gives a more natural edit sequence.