Longest Common Subsequence

class Solution {
public:
    int memo[1005][1005];
    int longestCommonSubsequence(string text1, string text2) {
        memset(memo, -1, sizeof(memo));
        return solve(0, 0, text1, text2);
    }
    int solve(int i, int j, string &s, string &t){
        if(i == s.size() || j == t.size())
            return 0;
        int &ans = memo[i][j];
        if(~ans) return ans;
        if(s[i] == t[j])
            ans = solve(i + 1, j + 1, s, t) + 1;
        else
            ans = max(solve(i + 1, j, s, t), solve(i, j + 1, s, t));
        return ans;
    }
};