input: def editDistance(string1: str, string2: str) -> int:
      """
      Compute the edit distance between two strings.
      
      >>> editDistance("kitten", "sitting")
      3
      >>> editDistance("cat", "bat")
      1
      >>> editDistance("hello", "world")
      4
      """
      m = len(string1)
      n = len(string2)
      # Create an empty matrix
      dp = [[0 for x in range(n+1)] for x in range(m+1)] 
    
      # Filling the first column of the matrix
      for i in range(m+1): 
          dp[i][0] = i 
    
      # Filling the second column of the matrix 
      for j in range(n+1): 
          dp[0][j] = j 
    
      # Populate the matrix
      for i in range(1, m+1): 
          for j in range(1, n+1): 
    
              if string1[i-1] == string2[j-1]: 
                  dp[i][j] = dp[i-1][j-1] 
              else: 
                  dp[i][j] = 1 + min(dp[i][j-1],        # Insert
                                     dp[i-1][j],        # Remove 
                                     dp[i-1][j-1])      # Replace
    
      return dp[m][n]
output:     m = len(string1)
      n = len(string2)
      # Create an empty matrix
      dp = [[0 for x in range(n+1)] for x in range(m+1)] 
    
      # Filling the first column of the matrix
      for i in range(m+1): 
          dp[i][0] = i 
    
      # Filling the second column of the matrix 
      for j in range(n+1): 
          dp[0][j] = j 
    
      # Populate the matrix
      for i in range(1, m+1): 
          for j in range(1, n+1): 
    
              if string1[i-1] == string2[j-1]: 
                  dp[i][j] = dp[i-1][j-1] 
              else: 
                  dp[i][j] = 1 + min(dp[i][j-1],        # Insert
                                     dp[i-1][j],        # Remove 
                                     dp[i-1][j-1])      # Replace
    
      return dp[m][n]