Given two strings text1 and text2, return the length of their longest common subsequence.
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. (eg, “ace” is a subsequence of “abcde” while “aec” is not). A common subsequence of two strings is a subsequence that is common to both strings.
If there is no common subsequence, return 0.
Example 1:
Input: text1 = "abcde", text2 = "ace"
Output: 3
Explanation: The longest common subsequence is "ace" and its length is 3. Example 2:
Input: text1 = "abc", text2 = "abc"
Output: 3
Explanation: The longest common subsequence is "abc" and its length is 3. Example 3:
Input: text1 = "abc", text2 = "def"
Output: 0
Explanation: There is no such common subsequence, so the result is 0.
Constraints:
1 <= text1.length <= 1000
1 <= text2.length <= 1000
The input strings consist of lowercase English characters only.
from functools import lru_cache
class Solution:
def longestCommonSubsequence(self, text1: str, text2: str) -> int:
self.t1 = text1
self.t2 = text2
return self.dc(len(text1)-1, len(text2)-1)
@lru_cache(None)
def dc(self, i, j):
if i < 0 or j < 0:
return 0
if self.t1[i] == self.t2[j]:
return self.dc(i-1, j-1) + 1
else:
return max(self.dc(i, j-1), self.dc(i-1, j))