Classic Levenshtein distance DP.
dp[i][j] = min edits to convert word1[:i] to word2[:j].
If last chars equal: dp[i-1][j-1].
Else: 1 + min(replace, delete, insert).
Use 1D rolling DP.
Classic Levenshtein distance DP.
dp[i][j] = min edits to convert word1[:i] to word2[:j].
If last chars equal: dp[i-1][j-1].
Else: 1 + min(replace, delete, insert).
Use 1D rolling DP.