题解 | #最长公共子串#

public:
    /**
     * longest common substring
     * @param str1 string字符串 the string
     * @param str2 string字符串 the string
     * @return string字符串
     */
    string LCS(string str1, string str2) {
        vector<vector<int>> dp(str1.size()+1, vector<int>(str2.size()+1, 0));
        int maxlength = 0;
        int maxlastindex = 0;
        for (int i=1; i<=str1.size(); i++){
            for (int j=1; j<=str2.size(); j++){
                if (str1[i-1] != str2[j-1]){
                    dp[i][j] = 0;
                } else{
                    dp[i][j] = dp[i-1][j-1] + 1;
                    if (dp[i][j] > maxlength){
                        maxlength = dp[i][j];
                        maxlastindex = i - 1;
                    }
                }
            }
        }
        return str1.substr(maxlastindex - maxlength + 1, maxlength);
        // write code here
    }
};