# [Solved] Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0. ## Question

Given two strings `text1` and `text2`, return the length of their longest common subsequenceIf there is no common subsequence, return `0`.

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"`.

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.

## 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]```