二叉查詢樹C語言實現及其視覺化
(1)若左子樹非空,則左子樹上的所有的節點的值都小於根節點的值
(2)若右子樹非空,則右子樹上的所有的節點的值都大於根節點的值
(3)其左右子樹都是二叉搜尋樹
1,二叉查詢樹的表示法
struct TreeNode; typedef struct TreeNode *PtrSearchTree; typedef PtrSearchTree SearchTree; struct TreeNode { int value; PtrSearchTree left; PtrSearchTree right; };
2,二叉查詢樹的插入:插入的元素始終位於葉子節點。
3,二叉查詢樹的建立,呼叫插入函式即可。void insert(SearchTree* tree, int value) { if( *tree == NULL ) { if( ! ((*tree) = (PtrSearchTree)malloc(sizeof(struct TreeNode))) ) { printf("insert malloc error\n"); exit(0); } (*tree)->value = value; (*tree)->left = (*tree)->right = NULL; } else { if( value < (*tree)->value ) insert(&((*tree)->left), value); else insert(&((*tree)->right), value); } }
note:
1 SearchTree tree = NULL;其中的 “= NULL”,在window下的gcc進行編譯執行時可以省略, 但是在linux編譯執行時如果沒有將其值設定為NULL, 則提醒了“段錯誤”。應該是編譯器的不同造成的, 不過為每個指標賦值,而不是由其變為野指標確實是個好的習慣。
2 getchar()是為了吃掉使用者輸入的數字之間的空格,並且在使用者輸入完成按下Enter鍵之後可以捕獲到‘\n’.
4, 二叉查詢樹的視覺化。為了對其進行視覺化,需要藉助與graphviz,他的安裝在上一篇中有簡單的介紹,並且其中使用的dot語言可在官網檢視,很容易學習。SearchTree create() { SearchTree tree = NULL; printf("Create Binary Search Tree\nplease enter the element, seperated by space, and stop input by Enter:\n"); int key; while(1) { scanf("%d", &key); insert(&tree, key); if( getchar() == '\n' ) break; } return tree; }
void visualization(SearchTree tree, char* filename)
{
FILE *fw;
if( NULL == (fw = fopen(filename, "w")) )
{
printf("open file error");
exit(0);
}
fprintf(fw, "digraph\n{\nnode [shape = Mrecord, style = filled, color = black, fontcolor = white];\n");
write2dot(tree, fw);
fprintf(fw, "}");
fclose(fw);
}
void write2dot(SearchTree tree, FILE* fw)
{
if(tree == NULL)
return ;
else
{
fprintf(fw, "%d [label = \"<f0> | <f1> %d | <f2> \", color = black, fontcolor = white, style = filled];\n", tree->value, tree->value);
}
if(tree->left)
{
fprintf(fw, "%d [label = \"<f0> | <f1> %d | <f2> \", color = black, fontcolor = white, style = filled];\n", tree->left->value, tree->left->value);
fprintf(fw, "%d:f0:sw -> %d:f1;\n", tree->value, tree->left->value);
}
if(tree->right)
{
fprintf(fw, "%d [label = \"<f0> | <f1> %d | <f2> \", color = black, fontcolor = white, style = filled];\n", tree->right->value, tree->right->value);
fprintf(fw, "%d:f2:se -> %d:f1;\n", tree->value, tree->right->value);
}
write2dot(tree->left, fw);
write2dot(tree->right, fw);
}
函式註釋:(1) visualization函式將引數tree指定的樹,使用dot語言寫入到引數filename指定的檔案中(檔案以.dot為字尾)
(2) write2dot函式相當於一個遍歷樹的過程,在遍歷過程中, 構成該樹的dot檔案。
程式的執行過程例項如下:
執行完成後會在同目錄下產生一個.dot檔案,在本程式中檔名為:searchtree.dot
使用dot命令產生圖片,如下圖所示,就生成了名為searchtree.png的圖片。
檢視圖片如下:
5, 二叉樹的刪除
若刪除元素為葉子節點,則直接刪除,將原本指向該節點的雙親節點的相應的指標域置空,
若刪除度為1的節點,將其輸出節點的子樹直接掛在刪除節點的父節點上,
若刪除度為2的節點,找其左子樹的最大值或者右子樹的最小值替代該節點的值,然後在其左子樹或者右子樹刪除找到的最大值或者最小值。
SearchTree delete(SearchTree tree, int value)
{
PtrSearchTree temp = NULL;
if( !tree )
{
printf("have no element(delete): %d\n", value);
return NULL;
}
else if( value < tree->value )
tree->left = delete(tree->left, value);
else if( value > tree->value )
tree->right = delete(tree->right, value);
else
{
if( tree->left && tree->right )
{
temp = find_min(tree->right);
tree->value = temp->value;
tree->right = delete(tree->right, temp->value);
}
else
{
temp = tree;
if( !(tree->left) )tree = tree->right;
else if( !(tree->right) )tree = tree->left;
free(temp);
}
}
return tree;
}
在程式中刪除83,得到如下的二叉樹:
6,查詢(遞迴和迭代)
note:函式的返回型別為指標型別。
SearchTree find_recursion(SearchTree tree, int value)
{
if( !tree )
{
printf("have no element(find): %d\n", value);
return NULL;
}
if( value < tree->value )
find_recursion(tree->left, value);
else if( value > tree->value )
find_recursion(tree->right, value);
else
return tree;
}
SearchTree find_iteration(SearchTree tree, int value)
{
while(tree)
{
if( value < tree->value )
tree = tree->left;
else if( value > tree->value )
tree = tree->right;
else
return tree;
}
printf("have no element(find): %d\n", value);
return NULL;
}
原始碼
#include<stdio.h>
#include<stdlib.h>
struct TreeNode;
typedef struct TreeNode *PtrSearchTree;
typedef PtrSearchTree SearchTree;
struct TreeNode
{
int value;
PtrSearchTree left;
PtrSearchTree right;
};
SearchTree create();
void insert(SearchTree* tree, int value);
void write2dot(SearchTree tree, FILE* fw);
void visualization(SearchTree tree, char* filename);
SearchTree find_min(SearchTree tree);
SearchTree find_max(SearchTree tree);
SearchTree find_iteration(SearchTree tree, int value);
SearchTree find_recursion(SearchTree tree, int value);
SearchTree delete(SearchTree tree, int value);
int main(int argc, char** argv)
{
SearchTree s_tree_1 = create();
visualization(s_tree_1, "searchtree.dot");
PtrSearchTree min = find_min(s_tree_1);
PtrSearchTree max = find_max(s_tree_1);
printf("the min and max is %d, %d, respectively\n", min->value, max->value);
int search = 83;
PtrSearchTree find_result_1 = find_iteration(s_tree_1, search);
PtrSearchTree find_result_2 = find_iteration(s_tree_1, search);
if( find_result_1 && find_result_2 )
printf("search for %d, and the result from iteration and recursion is: %d, %d\n", search, find_result_1->value, find_result_2->value);
s_tree_1 = delete(s_tree_1, 83);
visualization(s_tree_1, "searchtree_afterdelete.dot");
return 0;
}
SearchTree create()
{
SearchTree tree = NULL;
printf("Create Binary Search Tree\nplease enter the element, seperated by space, and stop input by Enter:\n");
int key;
while(1)
{
scanf("%d", &key);
insert(&tree, key);
if( getchar() == '\n' )
break;
}
return tree;
}
void insert(SearchTree* tree, int value)
{
if( *tree == NULL )
{
if( ! ((*tree) = (PtrSearchTree)malloc(sizeof(struct TreeNode))) )
{
printf("insert malloc error\n");
exit(0);
}
(*tree)->value = value;
(*tree)->left = (*tree)->right = NULL;
}
else
{
if( value < (*tree)->value )
insert(&((*tree)->left), value);
else
insert(&((*tree)->right), value);
}
}
void visualization(SearchTree tree, char* filename)
{
FILE *fw;
if( NULL == (fw = fopen(filename, "w")) )
{
printf("open file error");
exit(0);
}
fprintf(fw, "digraph\n{\nnode [shape = Mrecord, style = filled, color = black, fontcolor = white];\n");
write2dot(tree, fw);
fprintf(fw, "}");
fclose(fw);
}
void write2dot(SearchTree tree, FILE* fw)
{
if(tree == NULL)
return ;
else
{
fprintf(fw, "%d [label = \"<f0> | <f1> %d | <f2> \", color = black, fontcolor = white, style = filled];\n", tree->value, tree->value);
}
if(tree->left)
{
fprintf(fw, "%d [label = \"<f0> | <f1> %d | <f2> \", color = black, fontcolor = white, style = filled];\n", tree->left->value, tree->left->value);
fprintf(fw, "%d:f0:sw -> %d:f1;\n", tree->value, tree->left->value);
}
if(tree->right)
{
fprintf(fw, "%d [label = \"<f0> | <f1> %d | <f2> \", color = black, fontcolor = white, style = filled];\n", tree->right->value, tree->right->value);
fprintf(fw, "%d:f2:se -> %d:f1;\n", tree->value, tree->right->value);
}
write2dot(tree->left, fw);
write2dot(tree->right, fw);
}
SearchTree find_min(SearchTree tree)
{
if( !tree )
return NULL;
else
if( !(tree->left) ) return tree;
else
find_min(tree->left);
}
SearchTree find_max(SearchTree tree)
{
if( !tree )
return NULL;
else
if( !(tree->right) ) return tree;
else find_max(tree->right);
}
SearchTree find_recursion(SearchTree tree, int value)
{
if( !tree )
{
printf("have no element(find): %d\n", value);
return NULL;
}
if( value < tree->value )
find_recursion(tree->left, value);
else if( value > tree->value )
find_recursion(tree->right, value);
else
return tree;
}
SearchTree find_iteration(SearchTree tree, int value)
{
while(tree)
{
if( value < tree->value )
tree = tree->left;
else if( value > tree->value )
tree = tree->right;
else
return tree;
}
printf("have no element(find): %d\n", value);
return NULL;
}
SearchTree delete(SearchTree tree, int value)
{
PtrSearchTree temp = NULL;
if( !tree )
{
printf("have no element(delete): %d\n", value);
return NULL;
}
else if( value < tree->value )
tree->left = delete(tree->left, value);
else if( value > tree->value )
tree->right = delete(tree->right, value);
else
{
if( tree->left && tree->right )
{
temp = find_min(tree->right);
tree->value = temp->value;
tree->right = delete(tree->right, temp->value);
}
else
{
temp = tree;
if( !(tree->left) )tree = tree->right;
else if( !(tree->right) )tree = tree->left;
free(temp);
}
}
return tree;
}