Given two strings `text1`

and `text2`

, return the length of their longest common subsequence.

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. (eg, "ace" is a subsequence of "abcde" while "aec" is not). A *common subsequence* of two strings is a subsequence that is common to both strings.

If there is no common subsequence, return 0.

```
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.
```

Solution：

```
func longestCommonSubsequence(text1 string, text2 string) int {
len1 := len(text1)
len2 := len(text2)
//init dp
dp := make([][]int, len1+1)
for i := 0; i <= len1; i++ {
dp[i] = make([]int, len2+1)
}
for i := 1; i <=len1; i++ {
for j:= 1; j <=len2; j++ {
dp[i][j] = max(dp[i-1][j], dp[i][j-1])
if text1[i-1] == text2[j-1] {
dp[i][j] = max(dp[i][j], dp[i-1][j-1] + 1)
}
}
}
return dp[len1][len2]
}
func max(a, b int) int {
if a > b {
return a
}
return b
}
```