给定树中每个节点的结构，该结构如何在层上打印树，其中该结构包含节点的值及其父节点的值

Question

I have an array, where the index is the data of the node, and the value at that index is the parent of that node.

array = {2, 7, 5, 2, 7, 7, -1, 5, 2}
data ---- 1, 2, 3, 4, 5, 6, 7, 8, 9

I have to print this array as such:

7  
 2
  1
  4
  9
 5
  3
  8
 6

I have a struct that has the data from the array in two fields, value and parent, and than i created an array of t that holds those attributes for each node in the tree.

struct t{
    int value;
    int parent;
};
t tree[n];

Here is what I came up with for now. This prints the nodes in the correct order, but I have no idea how to add the spaces (" "), in order to highlight the levels of the tree. I hope you guys can give me some ideas.

void preetyPrint(t tree[], int n, int root)
{
    cout << root;
    cout << endl;

    for(int i = 0; i < n; i++)
    {
        if (tree[i].parent == root)
        {
            preetyPrint(tree, n, tree[i].value);
        }
    }
}

I'm sorry about the ambiguity of this question, I'm new here. Still learning to post good questions.

Answer 1

There are two approaches to this:

The int depth approach

You need to pass one more parameter to your function, an int depth .

When you call it from outside code, pass 0 for depth.

Then, in the recursive call inside prettyPrint() , invoke with depth + 1 .

Then, in your cout << root; replace it with cout << spaces << root;

And add some code which computes a spaces string to consist of a number of space characters. The number of spaces should be depth multiplied by whatever you want your indentation to be. (Say, 2, or 4.) The calculation of the spaces string is left as an exercise to the reader.

The string indentation approach

You need to pass one more parameter to your function, a string indentation .

When you call it from outside code, pass an empty string.

Then, in the recursive call inside prettyPrint() , invoke with indentation + " " (assuming that you want each indentation level to be 2 characters wide.)

Then, in your cout << root; replace it with cout << indentation << root;