1143. Longest Common Subsequence

Medium

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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.