ADS Praktikum 3 / ProofRBCriterion 2

int proofRBCriterion2(TreeNode* node) {
    TreeNode* left = node->getLeft();
    TreeNode* right = node->getRight();

    int height;
    int add = 0;

    if (left == nullptr && right == nullptr) {
        return 0;
    }
    else if (left == nullptr) {
        height = proofRBCriterion2(right);
        if (right->isBlack()) {
            add = 1;
        }
    }
    else if (right == nullptr) {
        height = proofRBCriterion2(left);
        if (left->isBlack()) {
            add = 1;
        }
    }
    else {
        int leftHeight = proofRBCriterion2(left);
        int rightHeight = proofRBCriterion2(right);

        if (left->isBlack()) {
            leftHeight += 1;
        }
        if (right->isBlack()) {
            rightHeight += 1;
        }

        if (leftHeight != rightHeight) {
            return -1;
        }

        height = leftHeight;
    }

    if (height == -1) {
        return -1;
    }

    return height + add;
}