二叉查找树的游标实现

数据结构与算法分析——c语言描述 练习4.11  答案

翻译错了，翻译成指针实现。看了英文原版。

tree.h

typedef int ElementType;
#define SpaceSize 100  
#ifndef _Tree_H
#define _Tree_H



typedef int PtrToNode;
typedef PtrToNode Position;
typedef PtrToNode SearchTree;

void initializeCursorSpace(void);

void makeEmpty(SearchTree t);
Position find(ElementType X, SearchTree t);
Position findMin(SearchTree t);
Position findMax(SearchTree t);
SearchTree insert(ElementType X, SearchTree t);
SearchTree Delete(ElementType X, SearchTree t);
ElementType Retrieve(Position p);
void Dir(SearchTree t);
#endif

tree.c

#include"tree.h"
#include"fatal.h"

struct TreeNode {
	ElementType element;
	SearchTree left;
	SearchTree right;
};

struct TreeNode cursorSpace[SpaceSize];

static PtrToNode cursorNew() {
	PtrToNode p;
	p = cursorSpace[0].left;
	cursorSpace[0].left = cursorSpace[p].left;
	return p;
}

static void cursorDispose(PtrToNode p) {
	cursorSpace[p].left = cursorSpace[0].left;
	cursorSpace[0].left = p;
}

void initializeCursorSpace(void) {
	for (int i = 0; i < SpaceSize-1; i++) {
		cursorSpace[i].left = i + 1;
	}
	cursorSpace[SpaceSize - 1].left = 0;
}

void makeEmpty(SearchTree t) {
	if (t) {
		makeEmpty(cursorSpace[t].left);
		makeEmpty(cursorSpace[t].right);
		cursorDispose(t);
	}
}

Position find(ElementType X, SearchTree t) {
	if (t == 0)
		return 0;//NOT FOUND
	else {
		if (X < cursorSpace[t].element)
			return find(X, cursorSpace[t].left);
		else if (X>cursorSpace[t].element)
			return find(X, cursorSpace[t].right);
		else
			return t;
	}
}

Position findMin(SearchTree t) {
	while (cursorSpace[t].left)
		t = cursorSpace[t].left;
	return t;
}

Position findMax(SearchTree t) {
	while (cursorSpace[t].right)
		t = cursorSpace[t].right;
	return t;
}

SearchTree insert(ElementType X, SearchTree t) {
	if (t == 0) {//包含树没有初始化
		t = cursorNew();
		if (t == 0)
			Error("out of cursorSpace");
		cursorSpace[t].element = X;
		cursorSpace[t].left = 0;
		cursorSpace[t].right = 0;
	}
	else {
		if (X < cursorSpace[t].element)
			cursorSpace[t].left = insert(X, cursorSpace[t].left);
		else if (X>cursorSpace[t].element)
			cursorSpace[t].right = insert(X, cursorSpace[t].right);
	}
	return t;//两种情况
}

SearchTree Delete(ElementType X, SearchTree t) {
	Position tempCell;
	if (t == 0) {
		Error("Element not found");
	}
	else if (X < cursorSpace[t].element)
		cursorSpace[t].left = Delete(X, cursorSpace[t].left);
	else if (X > cursorSpace[t].element)
		cursorSpace[t].right = Delete(X, cursorSpace[t].right);
	else if (cursorSpace[t].left && cursorSpace[t].right) {
		tempCell = findMin(cursorSpace[t].right);
		cursorSpace[t].element = cursorSpace[tempCell].element;
		cursorSpace[t].right = Delete(cursorSpace[t].element, cursorSpace[t].right);
	}
	else {
		tempCell = t;
		if (cursorSpace[t].left == 0)
			t = cursorSpace[t].right;
		else if (cursorSpace[t].right == 0)
			t = cursorSpace[t].left;
		cursorDispose(tempCell);
	}
	return t;
}

ElementType Retrieve(Position p) {
	return cursorSpace[p].element;
}

void Dir(SearchTree t) {
	if (t) {
		printf("%d ", cursorSpace[t].element);
		Dir(cursorSpace[t].left);
		Dir(cursorSpace[t].right);
	}
}

main.c

#include"tree.h"
#include<stdio.h>
int main() {
	initializeCursorSpace();
	SearchTree t = 0;

	t = insert(3, t);
	t = insert(1, t);
	t = insert(4, t);
	t = insert(6, t);
	t = insert(9, t);
	t = insert(2, t);
	t = insert(5, t);
	t = insert(7, t);

	Dir(t);
	printf("\n");
	Delete(3, t);

	Dir(t);
}