Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2. You have the following three operations: Insert, Delete, Replace a character.
0 <= word1.length, word2.length <= 500
2D DP where dp[i][j] = min ops to convert word1[0:i] to word2[0:j]. If chars match, dp[i][j] = dp[i-1][j-1]. Else take min of insert, delete, replace + 1.
def minDistance(word1, word2):
m, n = len(word1), len(word2)
dp = [[0] * (n + 1) for _ in range(m + 1)]
for i in range(m + 1):
dp[i][0] = i
for j in range(n + 1):
dp[0][j] = j
for i in range(1, m + 1):
for j in range(1, n + 1):
if word1[i-1] == word2[j-1]:
dp[i][j] = dp[i-1][j-1]
else:
dp[i][j] = 1 + min(dp[i-1][j], dp[i][j-1], dp[i-1][j-1])
return dp[m][n]