first try, looks bad, but working the second pass will be better

c/breadth-first-search.c

@@ -1,18 +1,7 @@
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 
-/*  Set up data structures to be able to support the breadth first search of a tree */
-typedef struct QNode {
-    int           value;
-    struct QNode* next;
-} QNode;
-
-typedef struct Q {
-    QNode* head;
-    QNode* tail;
-    int    length;
-} Q;
-
 typedef struct TreeNode {
     int              value;
     struct TreeNode* left;
@@ -23,6 +12,18 @@ typedef struct Tree {
     TreeNode* root;
 } Tree;
 
+/*  Set up data structures to be able to support the breadth first search of a tree */
+typedef struct QNode {
+    TreeNode*     tnode;  // this is the value of the QNode
+    struct QNode* next;
+} QNode;
+
+typedef struct Q {
+    QNode* head;
+    QNode* tail;
+    int    length;
+} Q;
+
 TreeNode* new_tree_node(int value) {
     TreeNode* node = malloc(sizeof(TreeNode));
     node->left = NULL;
@@ -32,10 +33,10 @@ TreeNode* new_tree_node(int value) {
     return (node);
 }
 
-QNode* new_qnode(int value) {
+QNode* new_qnode(TreeNode* tnode) {
     QNode* node = malloc(sizeof(QNode));
     node->next = NULL;
-    node->value = value;
+    node->tnode = tnode;
 
     return (node);
 }
@@ -46,6 +47,15 @@ Tree* new_tree(TreeNode* root) {
     return (tree);
 }
 
+Q* new_Q() {
+    Q* q = malloc(sizeof(Q));
+    q->head = NULL;
+    q->tail = NULL;
+    q->length = 0;
+
+    return (q);
+}
+
 void add_child_left(TreeNode* parent, TreeNode* node) {
     if (parent->left != NULL) {
         printf("ERROR: left child is non-empty\n");
@@ -78,11 +88,13 @@ void q_add_node(Q* q, QNode* node) {
 }
 
 // always remove from head
-void q_remove_node(Q* q) {
-    QNode* n = q->head;
+TreeNode* q_remove_node(Q* q) {
+    QNode*    n = q->head;
+    TreeNode* tnode_at_head = n->tnode;
     q->head = n->next;
     q->length--;
     free(n);
+    return (tnode_at_head);
 }
 
 /*
@@ -92,6 +104,31 @@ void q_remove_node(Q* q) {
 
  */
 
+bool bf_search(Tree tree, int value) {
+    // start by adding th eroot of tree to the q
+    Q*     search_path = new_Q();
+    QNode* n = new_qnode(tree.root);
+    q_add_node(search_path, n);
+    TreeNode* current_value;
+    while (search_path->length > 0) {
+        current_value = q_remove_node(search_path);
+
+        if (current_value->value == value) {
+            free(search_path);
+            return (true);
+        }
+
+        if (current_value->left != NULL) {
+            q_add_node(search_path, new_qnode(current_value->left));
+        }
+        if (current_value->right != NULL) {
+            q_add_node(search_path, new_qnode(current_value->right));
+        }
+    }
+    free(search_path);
+    return (false);
+}
+
 int main() {
     TreeNode* root = new_tree_node(10);
     Tree*     tree = new_tree(root);
@@ -104,4 +141,8 @@ int main() {
 
     add_child_left(root->right, new_tree_node(88));
     add_child_right(root->right, new_tree_node(14));
+
+    bool answer;
+    answer = bf_search(*tree, 90);
+    printf("the answer is %d\n", answer);
 }