edit-distance.py

# A Dynamic Programming based Python program for edit
# distance problem


def editDistDP(str1, str2, m, n):
    # Create a table to store results of subproblems
    dp = [[0 for x in range(n + 1)] for x in range(m + 1)]

    # Fill d[][] in bottom up manner
    for i in range(m + 1):
        for j in range(n + 1):

            # If first string is empty, only option is to
            # insert all characters of second string
            if i == 0:
                dp[i][j] = j  # Min. operations = j

            # If second string is empty, only option is to
            # remove all characters of second string
            elif j == 0:
                dp[i][j] = i  # Min. operations = i

            # If last characters are same, ignore last char
            # and recur for remaining string
            elif str1[i - 1] == str2[j - 1]:
                dp[i][j] = dp[i - 1][j - 1]

            # If last character are different, consider all
            # possibilities and find minimum
            else:
                dp[i][j] = 1 + min(
                    dp[i][j - 1], dp[i - 1][j], dp[i -
                                                   1][j - 1]  # Insert  # Remove
                )  # Replace

    return dp[m][n]


# Driver code
str1 = "sunday"
str2 = "saturday"

print(editDistDP(str1, str2, len(str1), len(str2)))