"""
Author : Turfa Auliarachman
Date : October 12, 2016

This is a pure Python implementation of Dynamic Programming solution to the edit
distance problem.

The problem is :
Given two strings A and B. Find the minimum number of operations to string B such that
A = B. The permitted operations are removal, insertion, and substitution.
"""


class EditDistance:
 """
 Use :
 solver = EditDistance()
 editDistanceResult = solver.solve(firstString, secondString)
 """

 def __init__(self):
 self.__prepare__()

 def __prepare__(self, N=0, M=0):
 self.dp = [[-1 for y in range(0, M)] for x in range(0, N)]

 def __solveDP(self, x, y):
 if x == -1:
 return y + 1
 elif y == -1:
 return x + 1
 elif self.dp[x][y] > -1:
 return self.dp[x][y]
 else:
 if self.A[x] == self.B[y]:
 self.dp[x][y] = self.__solveDP(x - 1, y - 1)
 else:
 self.dp[x][y] = 1 + min(
 self.__solveDP(x, y - 1),
 self.__solveDP(x - 1, y),
 self.__solveDP(x - 1, y - 1),
 )

 return self.dp[x][y]

 def solve(self, A, B):
 if isinstance(A, bytes):
 A = A.decode("ascii")

 if isinstance(B, bytes):
 B = B.decode("ascii")

 self.A = str(A)
 self.B = str(B)

 self.__prepare__(len(A), len(B))

 return self.__solveDP(len(A) - 1, len(B) - 1)


def min_distance_bottom_up(word1: str, word2: str) -> int:
 """
 >>> min_distance_bottom_up("intention", "execution")
 5
 >>> min_distance_bottom_up("intention", "")
 9
 >>> min_distance_bottom_up("", "")
 0
 """
 m = len(word1)
 n = len(word2)
 dp = [[0 for _ in range(n + 1)] for _ in range(m + 1)]
 for i in range(m + 1):
 for j in range(n + 1):

 if i == 0: # first string is empty
 dp[i][j] = j
 elif j == 0: # second string is empty
 dp[i][j] = i
 elif (
 word1[i - 1] == word2[j - 1]
 ): # last character of both substing is equal
 dp[i][j] = dp[i - 1][j - 1]
 else:
 insert = dp[i][j - 1]
 delete = dp[i - 1][j]
 replace = dp[i - 1][j - 1]
 dp[i][j] = 1 + min(insert, delete, replace)
 return dp[m][n]


if __name__ == "__main__":
 solver = EditDistance()

 print("****************** Testing Edit Distance DP Algorithm ******************")
 print()

 S1 = input("Enter the first string: ").strip()
 S2 = input("Enter the second string: ").strip()

 print()
 print("The minimum Edit Distance is: %d" % (solver.solve(S1, S2)))
 print("The minimum Edit Distance is: %d" % (min_distance_bottom_up(S1, S2)))
 print()
 print("*************** End of Testing Edit Distance DP Algorithm ***************")