C++实现二叉树遍历序列的求解方法

/*************************************************************************
 > File Name: Test.cpp
 > Author: SongLee
 ************************************************************************/
#include<iostream>
using namespace std;

struct TreeNode
{
  struct TreeNode* left;
  struct TreeNode* right;
  char elem;
};


TreeNode* PostOrderFromOrderings(char* inorder, char* preorder, int length)
{
  if(length == 0)
  {
    return NULL;
  }
  TreeNode* node = new TreeNode;
  node->elem = *preorder;
  int rootIndex = 0;
  for(; rootIndex < length; rootIndex++) // 求左子树的长度
  {
    if(inorder[rootIndex] == *preorder)
      break;
  }
  node->left = PostOrderFromOrderings(inorder, preorder + 1, rootIndex);
  node->right = PostOrderFromOrderings(inorder + rootIndex + 1, preorder + rootIndex + 1, length - (rootIndex + 1));
  cout << node->elem << " ";  // 求后序序列，所以最后输出根结点
  return node;
}

int main()
{
  char* pre = "ABDECFG";
  char* in = "DBEAFCG";
  PostOrderFromOrderings(in, pre, 7);
  cout << endl;
  return 0;
}

/*************************************************************************
 > File Name: Test1.cpp
 > Author: SongLee
 ************************************************************************/
#include<iostream>
using namespace std;

struct TreeNode
{
  struct TreeNode* left;
  struct TreeNode* right;
  char elem;
};

TreeNode* PreOrderFromOrderings(char* inorder, char* postorder, int length)
{
  if(length == 0)
  {
    return NULL;
  }
  TreeNode* node = new TreeNode;
  node->elem = postorder[length-1];
  int rootIndex = 0;
  for(; rootIndex < length; rootIndex++)  // 求左子树的长度
  {
    if(inorder[rootIndex] == postorder[length-1])
      break;
  }
  cout << node->elem << " ";  // 求先序序列，所以先输出根结点
  node->left = PreOrderFromOrderings(inorder, postorder, rootIndex);
  node->right = PreOrderFromOrderings(inorder + rootIndex + 1, postorder + rootIndex, length - (rootIndex + 1));
  return node;
}

int main()
{
  char* post = "DEBFGCA";
  char* in = "DBEAFCG";
  PreOrderFromOrderings(in, post, 7);
  cout << endl;
  return 0;
}