public int lcs(String str1, String str2) {

    int len1 = str1.length();
    int len2 = str2.length();

    int[][] dp = new int[len1 + 1][len2 + 1];

    int result = 0;
    for (int i = 0; i <= len1; i++) {
        for (int j = 0; j <= len2; j++) {
            if (i == 0 || j == 0)
                dp[i][j] = 0;
            else if (str1.charAt(i - 1) == str2.charAt(j - 1)) {
                dp[i][j] = dp[i - 1][j - 1] + 1;
            }

            else
                dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
        }
    }

    return dp[len1][len2];
}