Treap树实现文件C语言

 对于这个,想说的是.关于 NullNode 结点.在调用Release ()释放内存之后,要将其恢复为NULL,以便下次的连续使用.自己想到的,很不错.

/*treap.c -- treap树实现文件*/#include "treapTree.h"/*全局变量声明定义*/static Node * NullNode = NULL ;/*局部函数声明*/static Node * singleRotateWithLeft (Node * const pn) ;static Node * singleRotateWithRight (Node * const pn) ;static void release (const TreapTree tt) ;/*接口函数定义*/TreapTree Initialize_T (void){if (NULL == NullNode){NullNode = (Node *) malloc (sizeof (Node)) ;if (NULL == NullNode)return NULL ;NullNode -> left = NullNode -> right = NullNode ;NullNode -> priority = INFINITY ;srand ((unsigned int) time (NULL)) ;}return NullNode ;}TreapTree Insert_T (TreapTree tt, const Item item){if (tt == NullNode){/*Create and return a one-node tree.*/tt = (Node *) malloc (sizeof (Node)) ;if (NULL == tt)puts ("Out of space.") ;else{tt -> item = item ;tt -> priority = rand () ;tt -> left = tt -> right = NullNode ;}}else if (item < tt -> item){tt -> left = Insert_T (tt -> left, item) ;if (tt -> left -> priority < tt -> priority)tt = singleRotateWithLeft (tt) ;}else if (item > tt -> item){tt -> right = Insert_T (tt -> right, item) ;if (tt -> right -> priority < tt -> priority)tt = singleRotateWithRight (tt) ;}/*Otherwise it's a duplicate, do nothing.*/return tt ;}TreapTree Delete_T (TreapTree tt, const Item item){if (tt != NullNode){if (item < tt -> item)tt -> left = Delete_T (tt -> left, item) ;else if (item > tt -> item)tt -> right = Delete_T (tt -> right, item) ;else{/*Match found.*/if (tt -> left -> priority < tt -> right -> priority)tt = singleRotateWithLeft (tt) ;elsett = singleRotateWithRight (tt) ;if (tt != NullNode)/*Continue on down.*/tt = Delete_T (tt, item) ;else{/*At a leaf.*/free (tt -> left) ;tt -> left = NullNode ;}}}return tt ;}void Release_T (const TreapTree tt){release (tt) ;free (NullNode) ;/*For next Initialize_T ().*/NullNode = NULL ;}/*局部函数定义*/static Node * singleRotateWithLeft (Node * const pn){Node * child ;child = pn -> left ;pn -> left = child -> right ;child -> right = pn ;return child ;}static Node * singleRotateWithRight (Node * const pn){Node * child ;child = pn -> right ;pn -> right = child -> left ;child -> left = pn ;return child ;}static void release (const TreapTree tt){if (tt != NullNode){release (tt -> left) ;release (tt -> right) ;free (tt) ;}}

 

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