已知中序后序创建二叉树

#include<iostream.h>#include<string.h>#include<stdlib.h>#include<assert.h>template<class Type>class BinaryTree{public:struct TreeNode{Type data;TreeNode *leftchild, *rightchild;};BinaryTree() {}~BinaryTree(){}private:TreeNode *root;static TreeNode *_BuyNode(){TreeNode *p = (TreeNode *)malloc(sizeof(TreeNode));assert(p != NULL);return p;}static int find(Type *is, const Type &x, int n){for(int i = 0; i < n; ++i){if(is[i] == x)return i;}return -1;}static TreeNode *CreatInPost(Type *post, Type *is, int n){if(post == NULL || is == NULL || n ==0)return NULL;else{TreeNode *s = _BuyNode();s->data = post[n-1];int num = find(is, post[n-1], n);if(num == -1)exit(1);s->leftchild = CreatInPost(post, is,num);//此处放进去的是线序遍历的前num个s->rightchild = CreatInPost(post+num, is+num +1, n-num-1);//此处减1是因为这是从后序遍历中找的每次最后一个数就被使用了，每次到这里就要将它除掉return s;}}static void PreOrder(TreeNode *root){if(root != NULL){cout << root->data << " ";PreOrder(root->leftchild);PreOrder(root->rightchild);}}public:void Creat(Type *post, Type *is, int n){if(post != NULL && is != NULL)root = CreatInPost(post, is, n);}void PreOrder(){PreOrder(root);cout << endl;}};int main(void){BinaryTree<int> tree;int post[] = {34,56,67,45,23,89,78,12};int is[] = {34,23,56,45,67,12,78,89};int n = sizeof(post) / sizeof(post[0]);tree.Creat(post, is, n);tree.PreOrder();return 0;}