[数据结构与算法] : 二叉查找树
头文件
1 typedef int ElementType; 2 #ifndef _TREE_H_ 3 #define _TREE_H_ 4 5 struct TreeNode; 6 typedef struct TreeNode *Position; 7 typedef struct TreeNode *SearchTree; 8 9 SearchTree MakeEmpty(SearchTree T); 10 Position Find(ElementType X, SearchTree T); 11 Position FindMin(SearchTree T); 12 Position FindMin2(SearchTree T); 13 Position FindMax2(SearchTree T); 14 SearchTree Insert(ElementType X, SearchTree T); 15 SearchTree Delete(ElementType X, SearchTree T); 16 ElementType Retrieve(Position P); 17 18 #endif
源文件
1 #include "tree.h" 2 #include "fatal.h" 3 #include <malloc.h> 4 5 struct TreeNode 6 { 7 ElementType Element; 8 SearchTree Left; 9 SearchTree Right; 10 }; 11 12 // 先清空左子树, 再清空又子树, 再释放自身节点 13 SearchTree MakeEmpty(SearchTree T) 14 { 15 if(T != NULL) 16 { 17 MakeEmpty(T->Left); 18 MakeEmpty(T->Right); 19 free(T); 20 } 21 return NULL; // 递归终止条件 22 } 23 24 // 查找, 类似二分查找 25 Position Find(ElementType X, SearchTree T) 26 { 27 if(T == NULL) // 递归终止条件 28 return NULL; 29 if(X < T->Element) 30 return Find(X, T->Left); 31 else if(X > T->Element) 32 return Find(X, T->Right); 33 else 34 return T; 35 } 36 37 Position FindMin(SearchTree T) // 递归实现 38 { 39 if(T == NULL) // 防止非法输入 40 return NULL; 41 if(T->Left == NULL) // 递归终止 42 return T; 43 else 44 return FindMin(T->Left); 45 } 46 47 Position FindMin2(SearchTree T) // 非递归实现 48 { 49 if(T == NULL) 50 return NULL; 51 while(T->Left != NULL) 52 T = T->Left; 53 return T; 54 } 55 56 Position FindMax(SearchTree T) 57 { 58 if(T == NULL) 59 return NULL; 60 if(T->Right == NULL) 61 return T; 62 else 63 return FindMax(T->Right); 64 } 65 66 Position FindMax2(SearchTree T) 67 { 68 if(T == NULL) 69 return NULL; 70 while(T->Right != NULL) 71 T = T->Right; 72 return T; 73 } 74 75 // 插入 76 SearchTree Insert(ElementType X, SearchTree T) 77 { 78 if(T == NULL) // 如果T为NULL, 创建节点, 递归终止条件 79 { 80 T = (SearchTree)malloc(sizeof(struct TreeNode)); 81 if(T == NULL) 82 FatalError("Out of space!"); 83 else 84 { 85 T->Element = X; 86 T->Left = T->Right = NULL; 87 } 88 } 89 else if(X < T->Element) 90 T->Left = Insert(X, T->Left); 91 else if(X > T->Element) 92 T->Right = Insert(X, T->Right); 93 // 如果X已经在数中, 则什么也不做 94 return T; // Do not forget this line!! 95 } 96 97 // 删除 98 SearchTree Delete(ElementType X, SearchTree T) 99 { 100 Position TempCell; 101 if(T == NULL) // 递归终止 102 Error("Element not found!"); 103 else if(X < T->Element) 104 T->Left = Delete(X, T->Left); 105 else if(X > T->Element) 106 T->Right = Delete(X, T->Right); 107 else if(T->Left && T->Right) // Two children 108 { 109 TempCell = FindMin(T->Right);// 找一个替身, 右子树的最小值 110 T->Element = TempCell->Element; 111 T->Right = Delete(T->Element, T->Right);// 替身已经放到T->Element, 再从右子树删除该值即可 112 } 113 else // One or zero childern 114 { 115 TempCell = T; 116 if(T->Left == NULL) 117 T = T->Right; 118 else if(T->Right = NULL) 119 T = T->Left; 120 free(TempCell); 121 } 122 return T; // Do not forget this line!! 123 } 124 125 ElementType Retrieve(Position P) 126 { 127 return P->Element; 128 }
测试文件
1 #include "tree.h" 2 #include <stdio.h> 3 4 int main() 5 { 6 SearchTree T; 7 Position P; 8 int i = 0, j = 0; 9 10 T = MakeEmpty(NULL); 11 for( i = 0; i < 50; i++, j = ( j + 7 ) % 50 ) 12 T = Insert( j, T ); 13 for( i = 0; i < 50; i++ ) 14 if( ( P = Find( i, T ) ) == NULL || Retrieve( P ) != i ) 15 printf( "Error at %d\n", i ); 16 17 for( i = 0; i < 50; i += 2 ) 18 T = Delete( i, T ); 19 20 for( i = 1; i < 50; i += 2 ) 21 if( ( P = Find( i, T ) ) == NULL || Retrieve( P ) != i ) 22 printf( "Error at %d\n", i ); 23 for( i = 0; i < 50; i += 2 ) 24 if( ( P = Find( i, T ) ) != NULL ) 25 printf( "Error at %d\n", i ); 26 27 printf( "Min is %d, Max is %d\n", Retrieve( FindMin2( T ) ), 28 Retrieve( FindMax2( T ) ) ); 29 30 return 0; 31 }
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