lcs.cpp

int go(int i, int j) {
 
	if (i == n || j == m) return 0;
 
	int &ans = dp[i][j];
	if (ans != -1) return ans;
	ans = 0;
 
	int c1 = 0;
	if (s[i] == t[j]) {
		c1 = 1 + go(i + 1, j + 1);
	}
	int c2 = 0 + go(i + 1, j);
	int c3 = 0 + go(i, j + 1);
 
	return ans = max({c1, c2, c3});
}
// max_length = go(0, 0)