题解 | 最长公共子串

#include <vector>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 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) {
        int m = str1.length(), n = str2.length();
        vector<vector<int>> f(m + 1, vector<int> (n + 1, 0));
        int maxLength = 0, pos = 0;
        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (str1[i - 1] == str2[j - 1]) {
                    f[i][j] = f[i - 1][j - 1] + 1;
                } else {
                    f[i][j] = 0;
                }
                if (f[i][j] > maxLength) {
                    maxLength = f[i][j];
                    pos = i - 1;
                }
            }
        }
        return str1.substr(pos - maxLength + 1, maxLength);
    }
};