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: The two strings share no common subsequence, so the result is 0.
Examples
Example 1
Input: text1 = "abcde", text2 = "ace"
Output: 3
Explanation: The longest common subsequence is "ace" with length 3. Characters 'a', 'c', 'e' appear in both strings in the same relative order.
Example 2
Input: text1 = "abc", text2 = "abc"
Output: 3
Explanation: The entire string "abc" is a common subsequence since both strings are identical.
Constraints
- -1 <= text1.length, text2.length <= 1000
- -text1 and text2 consist of only lowercase English characters
Optimal Complexity
Time
O(m * n)
Space
O(m * n)
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