class Solution {
public:
string a, b;
int dp[1005][1005];
const int INF = 2e8;
int rec(int i, int j) {
    if(i == -1) {
        return 0;
    }
    if(j == -1) {
        return 0;
    }
    if(dp[i][j] != -1) {
        return dp[i][j];
    }
    int res = -INF;
    if(a[i] == b[j]) {
        res = max(res, rec(i - 1, j - 1) + 1);
    }
    res = max(res, rec(i - 1, j));
    res = max(res, rec(i, j - 1));
    return dp[i][j] = res;
}
    int longestCommonSubsequence(string text1, string text2) {
        a = text1;
        b = text2;
    memset(dp, -1, sizeof dp);
        return rec(a.size() - 1, b.size() - 1);
    }
};