Table of Contents

## Question

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:3Explanation:The longest common subsequence is "ace" and its length is 3.

**Example 2:**

Input:text1 = "abc", text2 = "abc"Output:3Explanation:The longest common subsequence is "abc" and its length is 3.

**Example 3:**

Input:text1 = "abc", text2 = "def"Output:0Explanation: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.

## Python Solution

class Solution: def longestCommonSubsequence(self, text1: str, text2: str) -> int: a = len(text1) b = len(text2) matrix = [[0 for _ in range(b+1)] for _ in range(a+1)] for i in range(1,a+1): for j in range(1,b+1): if text1[i-1]==text2[j-1]: matrix[i][j] = matrix[i-1][j-1]+1 else: matrix[i][j] = max(matrix[i-1][j],matrix[i][j-1]) return matrix[-1][-1]