文章目录
一、题目
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.
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: 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.
二、题解
cpp
class Solution {
public:
int longestCommonSubsequence(string text1, string text2) {
int n = text1.size(),m = text2.size();
vector<vector<int>> dp(n+1,vector<int>(m+1,0));
for(int i = 1;i <= n;i++){
for(int j = 1;j <= m;j++){
if(text1[i - 1] == text2[j - 1]) dp[i][j] = 1 + dp[i-1][j-1];
else dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
}
}
return dp[n][m];
}
};