int dpScore(char *A, char *B, int lenA, int lenB) {
    // initialize
    int score[lenA + 1][lenB + 1];
    for(int i = 0;i < lenA;i++) score[0][i] = -i;
    for(int i = 0;i < lenB;i++) score[i][0] = -i;

    // calculate
    for(int i = 1;i <= lenA;i++) {
        for(int j = 1;j <= lenB;j++) {
            if(A[i] == B[j]) { // match
                score[i][j] = score[i - 1][j - 1] + 2;
            }
            else { // not match
                score[i][j] = max(score[i][j - 1],
                                  score[i - 1][j],
                                  score[i - 1][j - 1]) - 1;
            }
        }
    }
    return score[lenA][lenB];
}