二叉排序樹的刪除操做

算法思想

二叉排序樹，刪除操做主要針對三種狀況。

1 葉子節點-直接刪除就能夠了

2 沒有左孩子的節點-直接嫁接右子樹就能夠了(沒有右孩子的節點-直接嫁接左子樹就能夠了)

3 若是左右子樹都存在，則尋找刪除節點的直接前驅（即左子樹裏面的最右的節點）

編程時須要注意，函數時針對指針的操做，所以爲了修改指針，要使用二級指針傳參才能夠

例如：

void delete(BinaryTree **b){ 　　.... } int main(){ 　　BinaryTree *b = (BinaryTree *)malloc(sizeof(BinaryTree)); 　　delete(&b); }

函數代碼：

bool deleteTree(BTree **b,int key){ if(!*b) return false; else{ if((*b)->data == key){ return deleteNode(&(*b)); } else if((*b)->data > key) return deleteTree(&(*b)->lchild,key); else
            return deleteTree(&(*b)->rchild,key); } } bool deleteNode(BTree **b){ BTree *p,*s; if((*b)->lchild == NULL ){ p = (*b); (*b) = (*b)->rchild; free(p); }else if((*b)->rchild == NULL){ p = (*b); (*b) = (*b)->lchild; free(p); }else{ p = (*b); s = (*b)->lchild; while(s->rchild != NULL){ p = s; s = s->rchild; } (*b)->data = s->data; if(p != (*b)) p->rchild = s->lchild; else p->lchild = s->lchild; free(s); return true; } }

所有代碼：

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 typedef struct bTree{  4     int data;  5     struct bTree *lchild,*rchild;  6 }BTree;  7 
 8 void initialTree(BTree *b);  9 bool insertTree(BTree *b,int key);  10 int searchTree(BTree *b,int key,BTree *f,BTree *&p);  11 void InOrderTree(BTree *b);  12 bool deleteTree(BTree **b,int key);  13 bool deleteNode(BTree **b);  14 
 15 int main(){  16     BTree *b = (BTree *)malloc(sizeof(BTree));  17     b->data = 5;  18     b->lchild = b->rchild = NULL;  19  initialTree(b);  20  InOrderTree(b);  21     deleteTree(&b,4);  22  InOrderTree(b);  23  getchar();  24     return 0;  25 }  26 bool deleteTree(BTree **b,int key){  27     if(!*b)  28         return false;  29     else{  30         if((*b)->data == key){  31             return deleteNode(&(*b));  32  }  33         else if((*b)->data > key)  34             return deleteTree(&(*b)->lchild,key);  35         else
 36             return deleteTree(&(*b)->rchild,key);  37  }  38 }  39 bool deleteNode(BTree **b){  40     BTree *p,*s;  41     if((*b)->lchild == NULL ){  42         p = (*b);  43         (*b) = (*b)->rchild;  44  free(p);  45     }else if((*b)->rchild == NULL){  46         p = (*b);  47         (*b) = (*b)->lchild;  48  free(p);  49     }else{  50         p = (*b);  51         s = (*b)->lchild;  52         while(s->rchild != NULL){  53             p = s;  54             s = s->rchild;  55  }  56         (*b)->data = s->data;  57         if(p != (*b))  58             p->rchild = s->lchild;  59         else
 60             p->lchild = s->lchild;  61  free(s);  62         return true;  63  }  64 }  65 void InOrderTree(BTree *b){  66     if( !b )  67         return;  68     InOrderTree(b->lchild);  69     printf("%d ",b->data);  70     InOrderTree(b->rchild);  71 }  72 
 73 void initialTree(BTree *b){  74     insertTree(b,5);  75     insertTree(b,3);  76     insertTree(b,4);  77     insertTree(b,6);  78     insertTree(b,2);  79     insertTree(b,1);  80     insertTree(b,8);  81 }  82 int searchTree(BTree *b,int key,BTree *f,BTree *&p){  83     if(!b){  84         p = f;  85         printf("++%d\n",p->data);  86         return 0;  87  }  88     else if( key == b->data){  89         p = b;  90         printf("--%d \n",p->data);  91         printf("找到元素key:%d\n",key);  92         return 1;  93  }  94     else if(key > b->data)  95         return searchTree(b->rchild,key,b,p);  96     else
 97         return searchTree(b->lchild,key,b,p);  98 }  99 bool insertTree(BTree *b,int key){ 100     BTree *p,*s; 101     if(!searchTree(b,key,NULL,p)){ 102         printf("%d 沒有出如今樹中，能夠插入在%d以後\n",key,p->data); 103         s = (BTree *)malloc(sizeof(BTree)); 104         s->data = key; 105         s->lchild = s->rchild = NULL; 106         if(!b){ 107             b = s; 108  } 109         else if(key < p->data){ 110             p->lchild = s; 111         }else{ 112             p->rchild = s; 113  } 114         return true; 115     }else
116         return false; 117 }

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運行示例：