伸展树

#include <stdio.h>
#include <stdlib.h>
//author : pgdnxu@qq.com

struct NODE
{
    NODE *left;
    NODE *right;
    NODE *pa;
    int data;
};

struct BST
{
    NODE *root;
    int nodenum;
};

NODE *search(int data,NODE *n)
{
    if(NULL == n)
        return NULL;
    if(data < n->data)
        return search(data,n->left);
    else if(data > n->data)
        return search(data,n->right);
    else
        return n;
}
NODE *find(int data,BST *t)
{
    if(NULL == t)
        return NULL;
    return search(data,t->root);
}

NODE *insert(int data,NODE **n,NODE *p)
{
    if(NULL == (*n))
    {
        (*n) = (NODE*)malloc(sizeof(NODE));
        (*n)->left = NULL;
        (*n)->right = NULL;
        (*n)->pa = p;
        (*n)->data = data;
        return *n;
    }
    if(data < (*n)->data)
    {
        //left
        return insert(data,&((*n)->left),*n);
    }
    else
    {
        return insert(data,&((*n)->right),*n);
    }
}

NODE *addNode(BST **t,int data)
{
    if(NULL == (*t))
    {
        (*t) = (BST*)malloc(sizeof(BST));
        (*t)->root = NULL;
        (*t)->nodenum = 0;
    }
    (*t)->nodenum++;
    return insert(data,&((*t)->root),NULL);
}
void init(BST **t,int data[],int num)
{
    int i;
    NODE *tmp;
    for(i=0;i<num;i++) {="" tmp="addNode(t,data[i]);" }="" void="" printtree(node="" *n,int="" deep)="" int="" i;="" for(i="0;i<deep;i++)" printf("="" ");="" if(null="=" n)="" printf("null\n");="" else="" if(n-="">pa == NULL)
        printf("%d--|\n",n->data);
    else
        printf("%d(p:%d)--|\n",n->data,n->pa->data);
    if(NULL != n)
    {
        printTree(n->left,deep+1);
        printTree(n->right,deep+1);
    }
}

void splay(NODE *n)
{
    //error
    if(NULL == n)
        return;
    NODE *nPa = n->pa;
    NODE *nPaPa = nPa == NULL ? NULL : nPa->pa;
    NODE *nPaPaPa=NULL;
    int lr = -1;
    if(nPaPa != NULL)
        nPaPaPa = nPaPa->pa;
    if(nPaPaPa != NULL)
    {
        if(nPaPa == nPaPaPa->left)
        {
            //left
            lr = 0;
        }
        else
        {
            //right
            lr = 1;
        }
    }
    //root return
    if(nPa == NULL)
    {
        return;
    }
    else if(nPaPa == NULL && n == nPa->left)
    {
        //zig
        printf("proc: zig\n");
        nPa->left = n->right;
        if(n->right != NULL)
            n->right->pa = nPa;
        n->pa = nPa->pa;
        nPa->pa = n;
        n->right = nPa;
    }
    else if(nPaPa == NULL && n == nPa->right)
    {
        //zag
        printf("proc: zag\n");
        nPa->right = n->left;
        if(n->left != NULL)
            n->left->pa = nPa;
        n->pa = nPa->pa;
        nPa->pa = n;
        n->left = nPa;
    }
    else if(n == nPa->left && nPa == nPaPa->left)
    {
        //zig-zig
        printf("proc: zig-zig\n");
        
        nPaPa->left = nPa->right;
        nPa->pa = nPaPa->pa;
        nPaPa->pa = nPa;
        nPa->right = nPaPa;

        nPa->left = n->right;
        if(n->right != NULL)
            n->right->pa = nPa;
        n->pa = nPa->pa;
        nPa->pa = n;
        n->right = nPa;

        if(lr != -1)
        {
            if(lr == 0)
                nPaPaPa->left = n;
            else if(lr == 1)
                nPaPaPa->right = n;
        }
        if(n->pa != NULL)
            splay(n);
    }
    else if(n == nPa->right && nPa == nPaPa->right)
    {
        //zag-zag
        printf("proc: zag-zag\n");
        
        nPaPa->right = nPa->left;
        nPa->pa = nPaPa->pa;
        nPaPa->pa = nPa;
        nPa->left = nPaPa;

        nPa->right = n->left;
        if(n->left != NULL)
            n->left->pa = nPa;
        n->pa = nPa->pa;
        nPa->pa = n;
        n->left = nPa;

        if(lr != -1)
        {
            if(lr == 0)
                nPaPaPa->left = n;
            else if(lr == 1)
                nPaPaPa->right = n;
        }
        if(n->pa != NULL)
            splay(n);
    }
    else if(n == nPa->left && nPa == nPaPa->right)
    {
        //zig-zag
        printf("proc: zig-zag\n");
        nPa->left = n->right;
        n->pa = nPa->pa;
        nPa->pa = n;
        n->right = nPa;

        nPaPa->right = n->left;
        if(n->left != NULL)
            n->left->pa = nPaPa;
        n->pa = nPaPa->pa;
        nPaPa->pa = n;
        n->left = nPaPa;

        if(lr != -1)
        {
            if(lr == 0)
                nPaPaPa->left = n;
            else if(lr == 1)
                nPaPaPa->right = n;
        }
        if(n->pa != NULL)
            splay(n);
    }
    else if(n == nPa->right && nPa == nPaPa->left)
    {
        //zag-zig
        printf("proc: zag-zig\n");
        nPa->right = n->left;
        n->pa = nPa->pa;
        nPa->pa = n;
        n->left = nPa;

        nPaPa->left = n->right;
        if(n->right != NULL)
            n->right->pa = nPaPa;
        n->pa = nPaPa->pa;
        nPaPa->pa = n;
        n->right = nPaPa;

        if(lr != -1)
        {
            if(lr == 0)
                nPaPaPa->left = n;
            else if(lr == 1)
                nPaPaPa->right = n;
        }
        if(n->pa != NULL)
            splay(n);
    }
}

NODE *sfind(int data,BST *t)
{
    if(NULL == t)
        return NULL;
    NODE *tar = search(data,t->root);
    if(tar != NULL)
    {
        splay(tar);
        t->root = tar;
    }
    else
        printf("tar is NULL!\n");
    return tar;
}


int main()
{
    int a[] = {6,5,4,3,2,1};    
    BST *tree;
    init(&tree,a,6);
    
    //case 1
    printf("========= case 1 =========\n");
    printTree(tree->root,0);
    sfind(1,tree);
    printf("--------------------------\n");
    printTree(tree->root,0);
    printf("==========================\n");
    //case 2
    printf("========= case 2 =========\n");
    printTree(tree->root,0);
    sfind(2,tree);
    printf("--------------------------\n");
    printTree(tree->root,0);
    printf("==========================\n");
    
    return 0;
}
</num;i++)></stdlib.h></stdio.h>