题解 | #公共子串计算#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) {
        BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
        String a, b;
        try {
            a = r.readLine();
            b = r.readLine();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        char[] chs1 = a.toCharArray();
        char[] chs2 = b.toCharArray();
        char[] tmp;
        int le1 = chs1.length, le2 = chs2.length, i;
        if (le1 > le2) {//保证小串在前
            i = le1;
            le1 = le2;
            le2 = i;
            tmp = chs1;
            chs1 = chs2;
            chs2 = tmp;
        }
        i = longestSubstr(chs1, chs2, le1 + 1, le2 + 1);
        System.out.print(i);
    }

    //常规动态规划求解
    protected static int longestSubstr(char[] chs1, char[] chs2, int m, int n) {
        int[][] dp = new int[m][n];
        int i = 1, j, max = 0;
        while (i < m) {
            j = 1;
            while (j < n) {
                if (chs1[i - 1] == chs2[j - 1]) {
                    dp[i][j] = 1 + dp[i - 1][j - 1];
                    max = dp[i][j] > max ? dp[i][j] : max;
                }
                j++;
            }
            i++;
        }
        return max;
    }
}