题干

• 已知：二叉树的先序序列和中序序列
• 求：后序序列
  

C++实现

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string>
using namespace std;struct TreeNode
{char data;TreeNode* left;TreeNode* right;
};TreeNode* Rebuild(string preOrder, string inOrder) {if (preOrder.size() == 0) {return NULL;}else {char rootdata = preOrder[0];//在先序中找到根TreeNode* pNew = new TreeNode;pNew->data = rootdata;int pos = inOrder.find(rootdata);//找到根在中序中的位置//preOrder.substr(1,pos)这是左子树的前序//inOrder.substr(0,pos)这是左子树的中序//preOrder.substr(pos+1,末尾)这是右子树的前序//inOrder.substr(pos+1,末尾)这是右子树的中序pNew->left = Rebuild(preOrder.substr(1, pos), inOrder.substr(0, pos));pNew->right = Rebuild(preOrder.substr(pos + 1), inOrder.substr(pos + 1));return pNew;}
}void postOrder(TreeNode* proot) {if (proot == NULL) {return;}else {postOrder(proot->left);postOrder(proot->right);printf("%c", proot->data);}
}int main() {char preOrder[30];char inOrder[30];while (scanf("%s%s", preOrder, inOrder) != EOF) {TreeNode* proot;proot = Rebuild(preOrder, inOrder);postOrder(proot);printf("\n");}return 0;
}