set up the ds needed to get the bfs implemented

c/breadth-first-search.c

@@ -0,0 +1,87 @@
+#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;
+    struct QNode* prev;
+} QNode;
+
+typedef struct Q {
+    QNode* head;
+    QNode* tail;
+} Q;
+
+typedef struct TreeNode {
+    int              value;
+    struct TreeNode* left;
+    struct TreeNode* right;
+} TreeNode;
+
+typedef struct Tree {
+    TreeNode* root;
+} Tree;
+
+TreeNode* new_tree_node(int value) {
+    TreeNode* node = malloc(sizeof(TreeNode));
+    node->left = NULL;
+    node->right = NULL;
+    node->value = value;
+
+    return (node);
+}
+
+QNode* new_qnode(int value) {
+    QNode* node = malloc(sizeof(QNode));
+    node->next = NULL;
+    node->prev = NULL;
+    node->value = value;
+
+    return (node);
+}
+
+Tree* new_tree(TreeNode* root) {
+    Tree* tree = malloc(sizeof(Tree));
+    tree->root = root;
+    return (tree);
+}
+
+void add_child_left(TreeNode* parent, TreeNode* node) {
+    if (parent->left != NULL) {
+        printf("ERROR: left child is non-empty\n");
+        exit(1);
+    } else {
+        parent->left = node;
+    }
+}
+
+void add_child_right(TreeNode* parent, TreeNode* node) {
+    if (parent->right != NULL) {
+        printf("ERROR: right child is non-empty\n");
+        exit(1);
+    } else {
+        parent->right = node;
+    }
+}
+
+/*
+                10
+            5        7
+        12    8    88    14
+
+ */
+
+int main() {
+    TreeNode* root = new_tree_node(10);
+    Tree*     tree = new_tree(root);
+
+    add_child_left(root, new_tree_node(5));
+    add_child_right(root, new_tree_node(7));
+
+    add_child_left(root->left, new_tree_node(12));
+    add_child_right(root->left, new_tree_node(8));
+
+    add_child_left(root->right, new_tree_node(88));
+    add_child_right(root->right, new_tree_node(14));
+}