Given two strings `text1`

and `text2`

, return *the length of their longest common subsequence. *If there is no

`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.

` ````
```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);
}
};

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