需要帮助穿越一棵树； 霍夫曼编码

Question

I have created a Huffman Tree and It appears to be correct, however I am weak when it comes to traversing data structures. I drew out the Tree on paper based on the information contained in my root tree and it appears to be well, however My code is faulty and I do not know hot to fix it.

The first 0 is persisting and, every time i take right, it seems to append a 0 after.

example:
L: 01
H: 1111

but my traversal gives me:
L: 001
H: 01010101

code Snippets

struct node
{
int symbol;
int frequency;
node* left;
node* right;
};

void Huffman::generateCode(node *tree, std::string code)
{
    if(tree->left == NULL && tree->right == NULL)
    {
        //std::cout << "Leaf Found: " << tree->symbol << "\t" << code << std::endl;
        mapCode.insert(std::pair<int, std::string>(tree->symbol,code));
    }
    if(tree->left != NULL)
    {
        code.append("0");
        generateCode(tree->left, code);
    }
    if(tree->right != NULL)
    {
        code.append("1");
        generateCode(tree->right, code);
    }
}

UPDATE SOLVED: i figure out that the code.append(); function was messing it up. i changed it too code + "0";

void Huffman::generateCode(node *tree, std::string code)
{
    if(tree->left == NULL && tree->right == NULL)
    {
        std::cout << "Leaf Found: " << tree->symbol << "\t" << code << std::endl;
        mapCode.insert(std::pair<int, std::string>(tree->symbol,code));
    }
    if(tree->left != NULL)
    {
        generateCode(tree->left, code + "0");
    }
    if(tree->right != NULL)
    {
        generateCode(tree->right, code + "1");
    }
}

Answer 1

you missed the else s:

void Huffman::generateCode(node *tree, std::string code)
{
    if(tree->left == NULL && tree->right == NULL)
    {
        //std::cout << "Leaf Found: " << tree->symbol << "\t" << code << std::endl;
        mapCode.insert(std::pair<int, std::string>(tree->symbol,code));
    }
    else if(tree->left != NULL)
    {
        code.append("0");
        generateCode(tree->left, code);
    }
    else if(tree->right != NULL)
    {
        code.append("1");
        generateCode(tree->right, code);
    }
}