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Populating next right pointers in each node
Signed-off-by: Leo Ma <begeekmyfriend@gmail.com>
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‎116_populating_next_right_pointers_in_each_node/Makefile

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all:
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gcc -O2 -o test connect.c

‎116_populating_next_right_pointers_in_each_node/connect.c

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#include <stdio.h>
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#include <stdlib.h>
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struct TreeLinkNode {
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int val;
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struct TreeLinkNode *left;
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struct TreeLinkNode *right;
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struct TreeLinkNode *next;
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};
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static void connect(struct TreeLinkNode *root)
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{
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struct TreeLinkNode *head = root;
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while (head->left != NULL) {
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struct TreeLinkNode *p;
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for (p = head; p != NULL; p = p->next) {
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p->left->next = p->right;
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p->right->next = p->next == NULL ? NULL : p->next->left;
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}
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head = head->left;
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}
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}
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int main(int argc, char **argv)
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{
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struct TreeLinkNode root, n1[2], n2[4], n3[8];
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root.val = 5;
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n1[0].val = 4;
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n1[1].val = 8;
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n2[0].val = 11;
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n2[2].val = 13;
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n2[3].val = 4;
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n3[0].val = 7;
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n3[1].val = 2;
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n3[6].val = 5;
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n3[7].val = 1;
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root.left = &n1[0];
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root.right = &n1[1];
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n1[0].left = &n2[0];
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n1[0].right = NULL;
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n1[0].next = NULL;
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n1[1].left = &n2[2];
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n1[1].right = &n2[3];
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n1[1].next = NULL;
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n2[0].left = &n3[0];
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n2[0].right = &n3[1];
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n2[0].next = NULL;
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n2[2].left = NULL;
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n2[2].right = NULL;
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n2[2].next = NULL;
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n2[3].left = &n3[6];
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n2[3].right = &n3[7];
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n2[3].next = NULL;
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n3[0].left = NULL;
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n3[0].right = NULL;
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n3[0].next = NULL;
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n3[1].left = NULL;
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n3[1].right = NULL;
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n3[1].next = NULL;
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n3[6].left = NULL;
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n3[6].right = NULL;
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n3[6].next = NULL;
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n3[7].left = NULL;
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n3[7].right = NULL;
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n3[7].next = NULL;
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connect(&root);
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return 0;
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}

‎117_populating_next_right_pointers_in_each_node_ii/Makefile

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all:
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gcc -O2 -o test connect.c

‎117_populating_next_right_pointers_in_each_node_ii/connect.c

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#include <stdio.h>
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#include <stdlib.h>
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struct TreeLinkNode {
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int val;
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struct TreeLinkNode *left;
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struct TreeLinkNode *right;
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struct TreeLinkNode *next;
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};
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#define container_of(ptr, type, member) \
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((type *)((char *)(ptr) - (size_t)&(((type *)0)->member)))
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#define list_entry(ptr, type, member) \
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container_of(ptr, type, member)
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#define list_first_entry(ptr, type, field) list_entry((ptr)->next, type, field)
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#define list_last_entry(ptr, type, field) list_entry((ptr)->prev, type, field)
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#define list_for_each(p, head) \
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for (p = (head)->next; p != (head); p = p->next)
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#define list_for_each_safe(p, n, head) \
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for (p = (head)->next, n = p->next; p != (head); p = n, n = p->next)
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struct list_head {
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struct list_head *next, *prev;
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};
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static inline void INIT_LIST_HEAD(struct list_head *list)
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{
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list->next = list->prev = list;
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}
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static inline int list_empty(const struct list_head *head)
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{
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return (head->next == head);
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}
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static inline void __list_add(struct list_head *new, struct list_head *prev, struct list_head *next)
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{
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next->prev = new;
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new->next = next;
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new->prev = prev;
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prev->next = new;
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}
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static inline void list_add(struct list_head *_new, struct list_head *head)
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{
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__list_add(_new, head, head->next);
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}
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static inline void list_add_tail(struct list_head *_new, struct list_head *head)
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{
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__list_add(_new, head->prev, head);
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}
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static inline void __list_del(struct list_head *entry)
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{
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entry->next->prev = entry->prev;
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entry->prev->next = entry->next;
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}
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static inline void list_del(struct list_head *entry)
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{
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__list_del(entry);
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entry->next = entry->prev = NULL;
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}
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struct bfs_node {
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struct TreeLinkNode *node;
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struct list_head link;
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};
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static struct bfs_node *node_fetch(struct list_head *free_list, struct TreeLinkNode *node)
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{
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struct bfs_node *bn = list_first_entry(free_list, struct bfs_node, link);
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list_del(&bn->link);
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bn->node = node;
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return bn;
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}
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static void queue(struct list_head *parents, struct list_head *children, struct list_head *free_list)
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{
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struct list_head *p, *n;
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struct TreeLinkNode *prev = NULL;
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list_for_each_safe(p, n, parents) {
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struct bfs_node *new;
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struct bfs_node *parent = list_entry(p, struct bfs_node, link);
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struct TreeLinkNode *lch = parent->node->left;
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struct TreeLinkNode *rch = parent->node->right;
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if (lch != NULL) {
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if (prev != NULL) {
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prev->next = lch;
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}
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prev = lch;
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new = node_fetch(free_list, lch);
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list_add_tail(&new->link, children);
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}
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if (rch != NULL) {
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if (prev != NULL) {
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prev->next = rch;
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}
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prev = rch;
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new = node_fetch(free_list, rch);
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list_add_tail(&new->link, children);
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}
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/* return */
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list_del(p);
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list_add(p, free_list);
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}
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}
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static void connect(struct TreeLinkNode *root)
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{
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if (root == NULL) {
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return;
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}
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struct list_head free_list;
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struct list_head q0;
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struct list_head q1;
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struct bfs_node nodes[4096];
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INIT_LIST_HEAD(&free_list);
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INIT_LIST_HEAD(&q0);
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INIT_LIST_HEAD(&q1);
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int i;
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for (i = 0; i < 4096; i++) {
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list_add(&nodes[i].link, &free_list);
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}
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int level = 0;
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struct bfs_node *new = node_fetch(&free_list, root);
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list_add_tail(&new->link, &q0);
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while (!list_empty(&q0) || !list_empty(&q1)) {
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if (level & 0x1) {
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queue(&q1, &q0, &free_list);
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} else {
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queue(&q0, &q1, &free_list);
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}
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level++;
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}
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}
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int main(int argc, char **argv)
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{
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struct TreeLinkNode root, n1[2], n2[4], n3[8];
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root.val = 5;
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n1[0].val = 4;
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n1[1].val = 8;
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n2[0].val = 11;
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n2[2].val = 13;
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n2[3].val = 4;
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n3[0].val = 7;
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n3[1].val = 2;
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n3[6].val = 5;
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n3[7].val = 1;
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root.left = &n1[0];
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root.right = &n1[1];
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n1[0].left = &n2[0];
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n1[0].right = NULL;
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n1[0].next = NULL;
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n1[1].left = &n2[2];
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n1[1].right = &n2[3];
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n1[1].next = NULL;
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n2[0].left = &n3[0];
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n2[0].right = &n3[1];
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n2[0].next = NULL;
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n2[2].left = NULL;
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n2[2].right = NULL;
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n2[2].next = NULL;
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n2[3].left = &n3[6];
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n2[3].right = &n3[7];
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n2[3].next = NULL;
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n3[0].left = NULL;
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n3[0].right = NULL;
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n3[0].next = NULL;
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n3[1].left = NULL;
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n3[1].right = NULL;
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n3[1].next = NULL;
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n3[6].left = NULL;
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n3[6].right = NULL;
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n3[6].next = NULL;
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n3[7].left = NULL;
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n3[7].right = NULL;
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n3[7].next = NULL;
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connect(&root);
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return 0;
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}

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