text: class Solution:
      """
      @param A, B: Two strings.
      @return: The length of longest common subsequence of A and B.
      """
  
      def longestCommonSubsequence(self, A, B):
          n, m = len(A), len(B)
          f = [[0] * (n + 1) for i in range(m + 1)]
          for i in range(n):
              for j in range(m):
                  f[i + 1][j + 1] = max(f[i][j + 1], f[i + 1][j])
                  if A[i] == B[j]:
                      f[i + 1][j + 1] = f[i][j] + 1
          return f[n][m]
  