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I am making a program to do a breadth first search.

The code which I am posting here just makes a que of the nodes visited in a binary tree in inorder fashion,so this implementation is not yet complete.

While developing I got a segmentation fault which I was not able to understand why I am getting so I am posting since the tree of same program (without BFS) is working.

```
#include<stdio.h>
#include<stdlib.h>
struct node {
struct node *left, *right;
int data, color;
} *root;
//root is used to point to the root node of tree
int check = 0;
typedef struct node tree;
struct list {
struct list *next;
struct node *btree_node_ptr; //btree_node_ptr stores the address of members of structure node
} *que_start;
typedef struct list que;
tree *create_node(int);
void add_tree(int value, tree *);
void travel_tree(tree *);
void enque(tree *);
void travel_que(void);
void deque(tree *);
que *que_add_node(tree *);
que *tree_que;
int main()
{
int i, j,value;
tree *nv;
root = NULL;
que_start = NULL;
value = 0;
while (0) {
printf("enter value \n");
scanf("%d", &value);
if (value == 1)
break;
if (root == NULL)
root = create_node(value);
else if (root != NULL) {
// nv = create_node(value);
add_tree(value, root);
}
}
travel_tree(root);
printf("\n travelling in que \n");
travel_que();
}
tree *create_node(int num)
{
tree *temp;
temp = (tree *) malloc(sizeof(tree));
temp->data = num;
temp->left = NULL;
temp->right = NULL;
temp->color=2;
return temp;
}
void add_tree(int v1, tree * node)
{
if (v1 <= node->data) {
if (node->left != NULL) {
add_tree(v1, node->left);
} else {
node->left = create_node(v1);
}
return;
}
if (v1 > node->data) {
if (node->right != NULL) {
add_tree(v1, node->right);
} else {
node->right = create_node(v1);
}
return;
}
}
void travel_tree(tree *temp)
{
// printf("\n inside travel_tree");
if (temp->left != NULL)
travel_tree(temp->left);
printf(" \n %d ", temp->data);
enque(temp);
if (temp->right != NULL)
travel_tree(temp->right);
return;
}
que *que_add_node(tree * temp)
{
que *b;
b = (que *) malloc(sizeof(que));
b->next = NULL;
temp->color=1;
b->btree_node_ptr = temp;
return b;
}
void enque(tree *temp)
{
//to make a que of que
tree_que=que_start;
if (que_start == NULL) {
que_start = que_add_node(temp);
tree_que=que_start;
return;
}
else
{ while(tree_que->next!=NULL)
{
tree_que=tree_que->next;
}
tree_que->next=que_add_node(temp);
}
return;
}
void travel_que(void)
{
tree_que=que_start;
while (tree_que!=NULL)
{
printf("Data is %d color is %d\n",tree_que->btree_node_ptr->data,tree_que->btree_node_ptr->color);
tree_que=tree_que->next;
}
return;
}
void deque (tree *temp)
{
while (tree_que!=NULL)
{
tree_que=tree_que->next;
}
return;
}
```