Longest Common Subsequence 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.

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, text2.length <= 1000 text1 and text2 consist of only lowercase English characters.

class Solution:
    def longestCommonSubsequence(self, text1: str, text2: str) -> int:
        
        dp = [[0] * (len(text2) + 1) for _ in range(len(text1) + 1)]
        
        for col in reversed(range(len(text2))):
            for row in reversed(range(len(text1))):
                if text2[col] == text1[row]:
                    dp[row][col] = 1 + dp[row + 1][col + 1]
                else:
                    dp[row][col] = max(dp[row + 1][col], dp[row][col + 1])
        
        return dp[0][0]

Solution().longestCommonSubsequence("abcde","ace")

3