### LeetCode Challenge #1143. Longest Common Subsequence

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.
##### Video Solution
###### C++ Solution
```				```
class Solution {
public:
int dp[1001][1001];
int lcs(string &text1, string &text2, int i, int j)
{
if(i==text1.size()|| j==text2.size())return 0;
if(dp[i][j]!=-1)return dp[i][j];
if(text1[i]==text2[j])return lcs(text1,text2,i+1,j+1)+1;
return dp[i][j]=max(lcs(text1,text2,i,j+1),lcs(text1,text2,i+1,j));
}
int longestCommonSubsequence(string text1, string text2) {
memset(dp,-1,sizeof(dp));
return lcs(text1,text2,0,0);
}
};
```
```