What algorithms can be used to draw a binary tree in the console? The tree is implemented in C. For example, a BST with numbers: 2 3 4 5 8 would be shown in the console as:
10 Answers
Check out Printing Binary Trees in Ascii
From @AnyOneElse Pastbin below:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!Code originally from /http://www.openasthra.com/c-tidbits/printing-binary-trees-in-ascii/
!!! Just saved it, cause the website is down.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Printing Binary Trees in Ascii
Here we are not going to discuss what binary trees are (please refer this, if you are looking for binary search trees), or their operations but printing them in ascii.
The below routine prints tree in ascii for a given Tree representation which contains list of nodes, and node structure is this
struct Tree
{
Tree * left, * right;
int element;
};
This pic illustrates what the below routine does on canvas..
ascii tree
Here is the printing routine..
b5855d39a6b8a2735ddcaa04a404c125001
Auxiliary routines..
//This function prints the given level of the given tree, assuming
//that the node has the given x cordinate.
void print_level(asciinode *node, int x, int level)
{
int i, isleft;
if (node == NULL) return;
isleft = (node->parent_dir == -1);
if (level == 0)
{
for (i=0; i<(x-print_next-((node->lablen-isleft)/2)); i++)
{
printf(" ");
}
print_next += i;
printf("%s", node->label);
print_next += node->lablen;
}
else if (node->edge_length >= level)
{
if (node->left != NULL)
{
for (i=0; i<(x-print_next-(level)); i++)
{
printf(" ");
}
print_next += i;
printf("/");
print_next++;
}
if (node->right != NULL)
{
for (i=0; i<(x-print_next+(level)); i++)
{
printf(" ");
}
print_next += i;
printf("\\");
print_next++;
}
}
else
{
print_level(node->left,
x-node->edge_length-1,
level-node->edge_length-1);
print_level(node->right,
x+node->edge_length+1,
level-node->edge_length-1);
}
}
//This function fills in the edge_length and
//height fields of the specified tree
void compute_edge_lengths(asciinode *node)
{
int h, hmin, i, delta;
if (node == NULL) return;
compute_edge_lengths(node->left);
compute_edge_lengths(node->right);
/* first fill in the edge_length of node */
if (node->right == NULL && node->left == NULL)
{
node->edge_length = 0;
}
else
{
if (node->left != NULL)
{
for (i=0; i<node->left->height && i < MAX_HEIGHT; i++)
{
rprofile[i] = -INFINITY;
}
compute_rprofile(node->left, 0, 0);
hmin = node->left->height;
}
else
{
hmin = 0;
}
if (node->right != NULL)
{
for (i=0; i<node->right->height && i < MAX_HEIGHT; i++)
{
lprofile[i] = INFINITY;
}
compute_lprofile(node->right, 0, 0);
hmin = MIN(node->right->height, hmin);
}
else
{
hmin = 0;
}
delta = 4;
for (i=0; i<hmin; i++)
{
delta = MAX(delta, gap + 1 + rprofile[i] - lprofile[i]);
}
//If the node has two children of height 1, then we allow the
//two leaves to be within 1, instead of 2
if (((node->left != NULL && node->left->height == 1) ||
(node->right != NULL && node->right->height == 1))&&delta>4)
{
delta--;
}
node->edge_length = ((delta+1)/2) - 1;
}
//now fill in the height of node
h = 1;
if (node->left != NULL)
{
h = MAX(node->left->height + node->edge_length + 1, h);
}
if (node->right != NULL)
{
h = MAX(node->right->height + node->edge_length + 1, h);
}
node->height = h;
}
asciinode * build_ascii_tree_recursive(Tree * t)
{
asciinode * node;
if (t == NULL) return NULL;
node = malloc(sizeof(asciinode));
node->left = build_ascii_tree_recursive(t->left);
node->right = build_ascii_tree_recursive(t->right);
if (node->left != NULL)
{
node->left->parent_dir = -1;
}
if (node->right != NULL)
{
node->right->parent_dir = 1;
}
sprintf(node->label, "%d", t->element);
node->lablen = strlen(node->label);
return node;
}
//Copy the tree into the ascii node structre
asciinode * build_ascii_tree(Tree * t)
{
asciinode *node;
if (t == NULL) return NULL;
node = build_ascii_tree_recursive(t);
node->parent_dir = 0;
return node;
}
//Free all the nodes of the given tree
void free_ascii_tree(asciinode *node)
{
if (node == NULL) return;
free_ascii_tree(node->left);
free_ascii_tree(node->right);
free(node);
}
//The following function fills in the lprofile array for the given tree.
//It assumes that the center of the label of the root of this tree
//is located at a position (x,y). It assumes that the edge_length
//fields have been computed for this tree.
void compute_lprofile(asciinode *node, int x, int y)
{
int i, isleft;
if (node == NULL) return;
isleft = (node->parent_dir == -1);
lprofile[y] = MIN(lprofile[y], x-((node->lablen-isleft)/2));
if (node->left != NULL)
{
for (i=1; i <= node->edge_length && y+i < MAX_HEIGHT; i++)
{
lprofile[y+i] = MIN(lprofile[y+i], x-i);
}
}
compute_lprofile(node->left, x-node->edge_length-1, y+node->edge_length+1);
compute_lprofile(node->right, x+node->edge_length+1, y+node->edge_length+1);
}
void compute_rprofile(asciinode *node, int x, int y)
{
int i, notleft;
if (node == NULL) return;
notleft = (node->parent_dir != -1);
rprofile[y] = MAX(rprofile[y], x+((node->lablen-notleft)/2));
if (node->right != NULL)
{
for (i=1; i <= node->edge_length && y+i < MAX_HEIGHT; i++)
{
rprofile[y+i] = MAX(rprofile[y+i], x+i);
}
}
compute_rprofile(node->left, x-node->edge_length-1, y+node->edge_length+1);
compute_rprofile(node->right, x+node->edge_length+1, y+node->edge_length+1);
}
Here is the asciii tree structure…
struct asciinode_struct
{
asciinode * left, * right;
//length of the edge from this node to its children
int edge_length;
int height;
int lablen;
//-1=I am left, 0=I am root, 1=right
int parent_dir;
//max supported unit32 in dec, 10 digits max
char label[11];
};
output:
2
/ \
/ \
/ \
1 3
/ \ / \
0 7 9 1
/ / \ / \
2 1 0 8 8
/
7
Some hints: the spacing between nodes at the same depth, (e.g., 2 and 4 or 3 and 8 in your example), is a function of the depth.
Each printed row consists of all nodes with the same depth, printed from the leftmost node to the rightmost node.
So you need a way to, for example, arrange your nodes in arrays of rows, according to their depth, in order of their left-most-ness.
Starting from the root node, a breadth-first search will visit nodes in the order of depth and left-most-ness.
Spacing between nodes can be found by finding the maximum height of the tree, using some constant width for the deepest nodes, and doubling that width for every lesser depth, so that the width for any depth = ( 1 + maxdepth - currentdepth ) * deepestwidth.
That number gives you the printed "horizontal width" of each node at any particular depth.
A left node is horizontally positioned in the left half of its parent's width, a righ node in the right half. You'll insert dummy spacers for any node that doesn't have parents; an easier way to do this would be to ensure that all leaves are at the same depth as the deepest node, with blank as their value. Obviously, you'll also have to compensate for the width of the values, perhaps by making the greatest depth's width at least as wide as the printed (decimal representaion, presumably) of he largest valued node.
Look at the output of pstree command in Linux. It does not produce the output in the exact form that you want, but IMHO it's more readable that way.
I second litb's recommendation. I had to do this lately to print the VAD tree of a Windows process and I used DOT language (just print out nodes from your binary tree walking function):
http://en.wikipedia.org/wiki/DOT_language
For example, your DOT file would contains:
digraph graphname {
5 -> 3;
5 -> 8;
3 -> 4;
3 -> 2;
}
You generate the graph with dotty.exe or convert it to PNG using dot.exe.
I think you shouldn't code that yourself, but have a look at Tree::Visualize which seems to be a nice Perl implementation with different possible styles and use/port one of the algorithms there.
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