红黑树插入的栈实现

来源：互联网发布：2016年上证指数数据编辑：程序博客网时间：2024/04/20 01:56
可以不使用parent 指针，直接使用栈实现，方法是在插入时记下插入结点的所有祖先结点，然后回溯时再使用，以下代码使用数组简单实现栈结构。
/* ================================================================== *//* no parent rbtree *//* ================================================================== */void __rb_np_rotate_left(struct rb_node *node, struct rb_node *parent, struct rb_root *root){    struct rb_node *right = node->right;    node->right = right->left;    right->left = node;    if (parent == NULL) {        root->rb_node = right;    }    else {        if (parent->left == node)            parent->left = right;        else            parent->right = right;    }}void __rb_np_rotate_right(struct rb_node *node, struct rb_node *parent, struct rb_root *root){    struct rb_node *left = node->left;    node->left = left->right;    left->right = node;    if (parent == NULL) {        root->rb_node = left;    }    else {        if (parent->left == node)            parent->left = left;        else            parent->right = left;    }}/* use s[0] as NULL pointer */#define PUSH_S(s, n, i) (s)[++(i)]=(n)#define POP_S(s, i)     (s)[(i)--]#define TOP_S(s, i)     (s)[(i)]static void rb_np_insert_color(struct rb_node *node, struct rb_root *root, struct rb_node **s, int i){    struct rb_node *parent, *uncle, *gparent, *tmp;    for (;;) {        parent = POP_S(s, i);        if (parent == NULL || parent->color == RB_BLACK) {            break;        }        gparent = POP_S(s, i);                if (parent == gparent->left) {            uncle = gparent->right;            if (uncle && uncle->color == RB_RED) { /* case 1 */                parent->color = RB_BLACK;                uncle->color = RB_BLACK;                gparent->color = RB_RED;                node = gparent;                continue;            }            if (parent->right == node) { /* case 2 */                __rb_np_rotate_left(parent, gparent, root);                tmp = node;                node = parent;                parent = tmp;            }            /* case 3 */            tmp = TOP_S(s, i);            __rb_np_rotate_right(gparent, tmp, root);            parent->color = RB_BLACK;            gparent->color = RB_RED;            break;        }        else {            uncle = gparent->left;            if (uncle && uncle->color == RB_RED) { /* case 1 */                parent->color = RB_BLACK;                uncle->color = RB_BLACK;                gparent->color = RB_RED;                node = gparent;                continue;            }            if (parent->left == node) { /* case 2 */                __rb_np_rotate_right(parent, gparent, root);                tmp = node;                node = parent;                parent = tmp;            }            /* case 3 */            tmp = TOP_S(s, i);            __rb_np_rotate_left(gparent, tmp, root);            parent->color = RB_BLACK;            gparent->color = RB_RED;            break;        }    }    root->rb_node->color = RB_BLACK;}    void rb_np_insert(struct rb_node *node, struct rb_root *root){    int i = 0;    struct rb_node *p = root->rb_node, *parent = NULL;    struct rb_node *s[1024] = {0, };    while (p) {        PUSH_S(s, p, i);        if (node->key < p->key)            p = p->left;        else            p = p->right;    }    node->left = node->right = NULL;        parent = TOP_S(s, i);    if (parent == NULL) {        node->color = RB_BLACK;        root->rb_node = node;    }    else {        node->color = RB_RED;        if (node->key < parent->key)            parent->left = node;        else             parent->right = node;        if (parent->color == RB_RED)            rb_np_insert_color(node, root, s, i);    }}