# Subject
Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0.

A subsequence of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.

For example, "ace" is a subsequence of "abcde".
A common subsequence of two strings is a subsequence that is common to both strings.

ade abe => ae


class Solution:
    def longestCommonSubsequence(self, text1: str, text2: str) -> int:
        
        mem = {}
        mem = {len(text1) + 1, len(text2) + 1}
        for p1 = 0 : len(text1) - 1
            for p2 0 : len(text2) - 1
                l1 = text1[p1]
                l2 = text2[p2]
            # a a  mem[1][1] = 1 + mem[0][0]
                if l1 == l2:
                    mem[p1 + 1][p2 + 1] = 1 + mem[p1][p2]
                else:
                    mem[p1 + 1][p2 + 1] = max(mem[p1+1, p2], mem[p1, p2+1])
        return mem[len(text1)][len(text2)]
    
    
        def helper(p1, p2):
            
#             mem[i][j] != null
            
            l1 = text1[p1]
            l2 = text2[p2]
            
            if l1 == l2:
                return mem[i][j] = 1 + mem[p1 -1][p2-1]
            else:
                return mem[i][j] = max(helper(p1, p2 + 1), helper(p1 + 1, p2))
            
        return helper(0, 0)  
            
#             if p1 == len(text1) or p2 == len(text2):
#                 return 0
            
#             if (p1, p2) in mem:
#                 return mem[(p1, p2)]
            
#             l1 = text1[p1]
#             occr = text2.find(l1, p2)
#             opt2 = 0
#             opt1 = helper(p1+1, p2)
            
#             if occr != -1:
#                 opt2 = 1+helper(p1+1, occr+1)
            
#             mem[(p1, p2)] = max(opt1, opt2)
            
#             return max(opt1, opt2)
        
#         return helper(0, 0)