Populating next right pointers in each node

Signed-off-by: Leo Ma <[email protected]>

116_populating_next_right_pointers_in_each_node/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test connect.c

116_populating_next_right_pointers_in_each_node/connect.c

@@ -0,0 +1,70 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct TreeLinkNode {
+    int val;
+    struct TreeLinkNode *left;
+    struct TreeLinkNode *right;
+    struct TreeLinkNode *next;
+};
+
+static void connect(struct TreeLinkNode *root)
+{
+    struct TreeLinkNode *head = root;
+    while (head->left != NULL) {
+        struct TreeLinkNode *p;
+        for (p = head; p != NULL; p = p->next) {
+            p->left->next = p->right;
+            p->right->next = p->next == NULL ? NULL : p->next->left;
+        }
+        head = head->left;
+    }
+}
+
+int main(int argc, char **argv)
+{
+    struct TreeLinkNode root, n1[2], n2[4], n3[8];
+    root.val = 5;
+    n1[0].val = 4;
+    n1[1].val = 8;
+    n2[0].val = 11;
+    n2[2].val = 13;
+    n2[3].val = 4;
+    n3[0].val = 7;
+    n3[1].val = 2;
+    n3[6].val = 5;
+    n3[7].val = 1;
+
+    root.left = &n1[0];
+    root.right = &n1[1];
+    n1[0].left = &n2[0];
+    n1[0].right = NULL;
+    n1[0].next = NULL;
+    n1[1].left = &n2[2];
+    n1[1].right = &n2[3];
+    n1[1].next = NULL;
+    n2[0].left = &n3[0];
+    n2[0].right = &n3[1];
+    n2[0].next = NULL;
+    n2[2].left = NULL;
+    n2[2].right = NULL;
+    n2[2].next = NULL;
+    n2[3].left = &n3[6];
+    n2[3].right = &n3[7];
+    n2[3].next = NULL;
+    n3[0].left = NULL;
+    n3[0].right = NULL;
+    n3[0].next = NULL;
+    n3[1].left = NULL;
+    n3[1].right = NULL;
+    n3[1].next = NULL;
+    n3[6].left = NULL;
+    n3[6].right = NULL;
+    n3[6].next = NULL;
+    n3[7].left = NULL;
+    n3[7].right = NULL;
+    n3[7].next = NULL;
+
+    connect(&root);
+    return 0;
+}

117_populating_next_right_pointers_in_each_node_ii/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test connect.c

117_populating_next_right_pointers_in_each_node_ii/connect.c

@@ -0,0 +1,194 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct TreeLinkNode {
+    int val;
+    struct TreeLinkNode *left;
+    struct TreeLinkNode *right;
+    struct TreeLinkNode *next;
+};
+
+#define container_of(ptr, type, member) \
+    ((type *)((char *)(ptr) - (size_t)&(((type *)0)->member)))
+
+#define list_entry(ptr, type, member) \
+    container_of(ptr, type, member)
+
+#define	list_first_entry(ptr, type, field)  list_entry((ptr)->next, type, field)
+#define	list_last_entry(ptr, type, field)  list_entry((ptr)->prev, type, field)
+
+#define	list_for_each(p, head) \
+	for (p = (head)->next; p != (head); p = p->next)
+
+#define	list_for_each_safe(p, n, head) \
+	for (p = (head)->next, n = p->next; p != (head); p = n, n = p->next)
+
+struct list_head {
+    struct list_head *next, *prev;
+};
+
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+    list->next = list->prev = list;
+}
+
+static inline int list_empty(const struct list_head *head)
+{
+    return (head->next == head);
+}
+
+static inline void __list_add(struct list_head *new, struct list_head *prev, struct list_head *next)
+{
+    next->prev = new;
+    new->next = next;
+    new->prev = prev;
+    prev->next = new;
+}
+
+static inline void list_add(struct list_head *_new, struct list_head *head)
+{
+    __list_add(_new, head, head->next);
+}
+
+static inline void list_add_tail(struct list_head *_new, struct list_head *head)
+{
+    __list_add(_new, head->prev, head);
+}
+
+static inline void __list_del(struct list_head *entry)
+{
+    entry->next->prev = entry->prev;
+    entry->prev->next = entry->next;
+}
+
+static inline void list_del(struct list_head *entry)
+{
+    __list_del(entry);
+    entry->next = entry->prev = NULL;
+}
+
+struct bfs_node {
+    struct TreeLinkNode *node;
+    struct list_head link;
+};
+
+static struct bfs_node *node_fetch(struct list_head *free_list, struct TreeLinkNode *node)
+{
+    struct bfs_node *bn = list_first_entry(free_list, struct bfs_node, link);
+    list_del(&bn->link);
+    bn->node = node;
+    return bn;
+}
+
+static void queue(struct list_head *parents, struct list_head *children, struct list_head *free_list)
+{
+    struct list_head *p, *n;
+    struct TreeLinkNode *prev = NULL;
+    list_for_each_safe(p, n, parents) {
+        struct bfs_node *new;
+        struct bfs_node *parent = list_entry(p, struct bfs_node, link);
+        struct TreeLinkNode *lch = parent->node->left;
+        struct TreeLinkNode *rch = parent->node->right;
+        if (lch != NULL) {
+            if (prev != NULL) {
+                prev->next = lch;
+            }
+            prev = lch;
+            new = node_fetch(free_list, lch);
+            list_add_tail(&new->link, children);
+        }
+        if (rch != NULL) {
+            if (prev != NULL) {
+                prev->next = rch;
+            }
+            prev = rch;
+            new = node_fetch(free_list, rch);
+            list_add_tail(&new->link, children);
+        }
+
+        /* return */
+        list_del(p);
+        list_add(p, free_list);
+    }
+}
+
+static void connect(struct TreeLinkNode *root)
+{
+    if (root == NULL) {
+        return;
+    }
+
+    struct list_head free_list;
+    struct list_head q0;
+    struct list_head q1;
+    struct bfs_node nodes[4096];
+    INIT_LIST_HEAD(&free_list);
+    INIT_LIST_HEAD(&q0);
+    INIT_LIST_HEAD(&q1);
+
+    int i;
+    for (i = 0; i < 4096; i++) {
+        list_add(&nodes[i].link, &free_list);
+    }
+
+    int level = 0;
+    struct bfs_node *new = node_fetch(&free_list, root);
+    list_add_tail(&new->link, &q0);
+
+    while (!list_empty(&q0) || !list_empty(&q1)) {
+        if (level & 0x1) {
+            queue(&q1, &q0, &free_list);
+        } else {
+            queue(&q0, &q1, &free_list);
+        }
+        level++;
+    }
+}
+
+int main(int argc, char **argv)
+{
+    struct TreeLinkNode root, n1[2], n2[4], n3[8];
+    root.val = 5;
+    n1[0].val = 4;
+    n1[1].val = 8;
+    n2[0].val = 11;
+    n2[2].val = 13;
+    n2[3].val = 4;
+    n3[0].val = 7;
+    n3[1].val = 2;
+    n3[6].val = 5;
+    n3[7].val = 1;
+
+    root.left = &n1[0];
+    root.right = &n1[1];
+    n1[0].left = &n2[0];
+    n1[0].right = NULL;
+    n1[0].next = NULL;
+    n1[1].left = &n2[2];
+    n1[1].right = &n2[3];
+    n1[1].next = NULL;
+    n2[0].left = &n3[0];
+    n2[0].right = &n3[1];
+    n2[0].next = NULL;
+    n2[2].left = NULL;
+    n2[2].right = NULL;
+    n2[2].next = NULL;
+    n2[3].left = &n3[6];
+    n2[3].right = &n3[7];
+    n2[3].next = NULL;
+    n3[0].left = NULL;
+    n3[0].right = NULL;
+    n3[0].next = NULL;
+    n3[1].left = NULL;
+    n3[1].right = NULL;
+    n3[1].next = NULL;
+    n3[6].left = NULL;
+    n3[6].right = NULL;
+    n3[6].next = NULL;
+    n3[7].left = NULL;
+    n3[7].right = NULL;
+    n3[7].next = NULL;
+
+    connect(&root);
+    return 0;
+}