《剑指offer》面试题6重建二叉树

#include <iostream>using namespace std;typedef struct Binary_Node{    int value;    struct Binary_Node *left;    struct Binary_Node *right;}BinaryNode;int pre_order[1010];int in_order[1010];int flag;BinaryNode *BuildTree(int *start_pre,int *end_pre,                      int *start_in,int *end_in){    BinaryNode *root=new BinaryNode;    root->value=*start_pre;    root->left=root->right=NULL;    if(start_pre== end_pre)    {        if(start_in==end_in && *start_pre==*start_in)            return root;        else        {            flag=0;        }    }    //在中跟序列中找到根节点的值    int *rootInOrder=start_in;    while(rootInOrder<=end_in&& *rootInOrder!=root->value)        rootInOrder++;    int leftLength  = rootInOrder-start_in;    int rightLength = end_in - rootInOrder;    int *leftPriEnd = start_pre+leftLength;    if (leftLength >0)    {        root->left= BuildTree(start_pre+1,leftPriEnd,start_in,rootInOrder-1);    }    else    {        //flag=0;    }    if(leftLength<end_pre- start_pre)    {        root->right=BuildTree(leftPriEnd+1,end_pre,rootInOrder+1,end_in);    }    else    {        //flag=0;    }    return root;}void print(BinaryNode *root){    if(root!=NULL)    {        print(root->left);        print(root->right);        if(root!=NULL)        {            cout<<root->value<<' ';        }    }}int main(){    int length;    while(cin>>length)    {        for(int i=0;i<length;i++)            cin>>*(pre_order+i);        for(int i=0;i<length;i++)            cin>>*(i+in_order);        flag=1;        BinaryNode *node=new BinaryNode;        int *start_pre=&pre_order[0];        int *end_pre  =&pre_order[length-1];        int *start_in =&in_order[0];        int *end_in   =&in_order[length-1];        node=BuildTree(start_pre,end_pre,start_in,end_in);        if (flag)        {            print(node);            cout<<endl;        }        else cout<<"No"<<endl;    }    return 0;}