解题步骤：

参考代码：

class Solution {
public:
    int findLength(vector<int>& nums1, vector<int>& nums2) {
        int m = nums1.size();
        int n = nums2.size();
        //多开一行，多开一列
        vector<vector<int>> dp(m + 1, vector<int>(n + 1));
        int ret = 0;

        for (size_t i = 1; i <= m; i++)
        {
            for (size_t j = 1; j <= n; j++)
            {
                if (nums1[i-1] == nums2[j-1])
                {
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                }
                else
                {
                    dp[i][j] = 0;
                }
                ret = max(ret, dp[i][j]);
            }
        }
        return ret;
    }
};

你学会了吗？？？