poj2255

重构二叉树，已知前序和中序，输出后序。

#include <iostream>
#include <cstring>
using namespace std;

struct treeNode
{
 treeNode();
 char letter;
 treeNode* left;
 treeNode* right;
};
treeNode::treeNode()
{
 left=NULL;
 right=NULL;
}
void AddNode(treeNode* node,bool left,bool right,char ch)
{
 treeNode* tmpNode=new treeNode;
 tmpNode->letter=ch;

 if(true==left)
 {
  node->left=tmpNode;
 }
 else
 {
  node->right=tmpNode;
 }
}
int findSameLetter(char letter,char str[],int startPoint)
{
 int len=0;
 for(int i=startPoint;str[i]!='/0';i++)
 {
  
  if(str[i]==letter)
  { 
   break;
  }
  len++;
  
 }
 return len;
}
void BuildTree(treeNode* cNode,char preStr[],char inStr[], int preStart,int inStart,int preEnd,int inEnd)
{
 //把preStr[preStart]建立新的节点
 cNode->letter=preStr[preStart];
 //调用findSameStr[]找到左子树的共同字符串长度
 int len;
 len=findSameLetter(cNode->letter,inStr,inStart);
 if(len>0)//对左子树调用BuildTree  
 {
  cNode->left=new treeNode;
  BuildTree(cNode->left,preStr,inStr,preStart+1,inStart,preStart+len,inStart+len-1);
 }
 //对右子树调用BuildTree
 if(preStart+len+1<=preEnd)
 {
  cNode->right=new treeNode;
  BuildTree(cNode->right,preStr,inStr,preStart+len+1,inStart+len+1,preEnd,inEnd);
 }
}
void PostTravel(treeNode* node)
{
 if(NULL!=node)
 {
  PostTravel(node->left);
  PostTravel(node->right);
  cout<<node->letter;
 }
 return;
}
int main()
{
 char preStr[27];
 char inStr[27];
 int len;
 treeNode* rootNode=NULL;
 while(cin>>preStr>>inStr)
 {
  len=strlen(preStr)-1;
  rootNode=new treeNode;
  BuildTree(rootNode,preStr,inStr,0,0,len,len);
  PostTravel(rootNode);
  cout<<endl;
 }
 return 0;
}