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.
"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: 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 <= 1000text1 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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