A certain level of a binary tree to array - c

Question

I need to put inside an array, the values of a binary tree, but the thing is, I should only put inside the array the values that are at a certain depth. And it should output the number of elements inserted at the array.
I have made this:
int nivel2_(ABin a, int n, int v[], int level, int *i){
int t;
if(!a) return 0;
if(n == level){
v[(*i)++] = a->value;
return 1;
}else{
t = nivel2_(a->left, n, v, level+1, i) + nivel2_(a->right, n, v, level+1, i);
}
return t;
}
int nivel2(ABin a, int n, int v[]){
int k = 0;
int *i;
i = &k;
return nivel2_(a, n, v, 1, i);
}
As I will keep changing the index recursively and only when we reach the depth we want, I thought of using a pointer, this way, when one part of the recursive folding happens it will change the value to all the other folding processes. Makes sense?
Structures:
typedef struct slist
{
int value;
struct slist* next;
} *SList;
typedef struct arvbin* ABin;
typedef struct arvbin
{
int value;
ABin right;
ABin left;
} arvb;
DOES IT WORK?
Only when I want the elements of the first level of depth!
Calling like this:
nivel2(tree2, 1, v);
Complete code
#include <stdio.h>
#include <stdlib.h>
typedef struct slist
{
int value;
struct slist* next;
} *SList;
typedef struct arvbin* ABin;
typedef struct arvbin
{
int value;
ABin right;
ABin left;
} arvb;
int nivel2_(ABin a, int n, int v[], int level, int *i){
int t;
if(!a) return 0;
if(n == level){
v[(*i)++] = a->value;
return 1;
}else{
t = nivel2_(a->left, n, v, level+1, i) + nivel2_(a->right, n, v, level+1, i);
}
return t;
}
int nivel2(ABin a, int n, int v[]){
int k = 0;
int *i;
i = &k;
return nivel2_(a, n, v, 1, i);
}
void insertTree(ABin *tree, int val){
if((*tree)==NULL){
*tree = (ABin) malloc(sizeof(arvb));
(*tree)->value = val;
(*tree)->left = NULL;
(*tree)->right = NULL;
return;
}
else if(val > (*tree)->value)
{
insertTree(&((*tree)->right), val);
}
else if(val <= (*tree)->value)
{
insertTree(&((*tree)->left), val);
}
return;
}
int main(){
int v[10] = {0};
ABin tree2 = NULL;
insertTree(&tree2, 22);
insertTree(&tree2, 1);
insertTree(&tree2, 3);
nivel2(tree2, 1, v);
int i;
for(i=0; i<5; i++){
printf("%d\n", v[i]);
}
return 0;
}

Answer 1

The code looks mostly OK to me. Here's a mildly modified version, mainly with a tree printing function added, and some diagnostics, and an extended tree. My suspicion is that you expected your tree to have just 2 levels, but it actually had 3.
Code
#include <stdio.h>
#include <stdlib.h>
typedef struct slist
{
int value;
struct slist* next;
} *SList;
typedef struct arvbin* ABin;
typedef struct arvbin
{
int value;
ABin right;
ABin left;
} arvb;
static int nivel2_(ABin a, int n, int v[], int level, int *i)
{
int t = 0;
if (a)
{
if (n == level)
{
v[(*i)++] = a->value;
t = 1;
}
else
{
t += nivel2_(a->left, n, v, level + 1, i);
t += nivel2_(a->right, n, v, level + 1, i);
}
}
return t;
}
static int nivel2(ABin a, int n, int v[])
{
int k = 0;
int r = nivel2_(a, n, v, 1, &k);
printf("r = %d; k = %d\n", r, k);
return k;
}
static
void insertTree(ABin *tree, int val)
{
if ((*tree) == NULL)
{
*tree = (ABin) malloc(sizeof(arvb));
(*tree)->value = val;
(*tree)->left = NULL;
(*tree)->right = NULL;
return;
}
else if (val > (*tree)->value)
{
insertTree(&((*tree)->right), val);
}
else if (val <= (*tree)->value)
{
insertTree(&((*tree)->left), val);
}
}
static void tree_to_array(ABin tree, int level)
{
int v[10] = { 0 };
int n = nivel2(tree, level, v);
printf("Converted level %d to array:", level);
for (int i = 0; i < n; i++)
printf(" %d", v[i]);
putchar('\n');
}
static void print_tree(ABin tree, int level)
{
if (tree != 0)
{
printf("Level %d: %d\n", level, tree->value);
print_tree(tree->left, level + 1);
print_tree(tree->right, level + 1);
}
}
int main(void)
{
ABin tree2 = NULL;
insertTree(&tree2, 22);
insertTree(&tree2, 10);
insertTree(&tree2, 13);
insertTree(&tree2, 33);
insertTree(&tree2, 39);
insertTree(&tree2, 43);
insertTree(&tree2, 19);
print_tree(tree2, 1);
for (int level = 1; level < 5; level++)
tree_to_array(tree2, level);
return 0;
}
Sample output
Level 1: 22
Level 2: 10
Level 3: 13
Level 4: 19
Level 2: 33
Level 3: 39
Level 4: 43
r = 1; k = 1
Converted level 1 to array: 22
r = 2; k = 2
Converted level 2 to array: 10 33
r = 2; k = 2
Converted level 3 to array: 13 39
r = 2; k = 2
Converted level 4 to array: 19 43
That looks correct to me for the tree shape that's printed.